diff --git a/Library/Homebrew/cask/artifact/moved.rb b/Library/Homebrew/cask/artifact/moved.rb
index d3c5331639..b80e0a6ef7 100644
--- a/Library/Homebrew/cask/artifact/moved.rb
+++ b/Library/Homebrew/cask/artifact/moved.rb
@@ -180,7 +180,7 @@ module Cask
 
       def delete(target, force: false, successor: nil, command: nil, **_)
         ohai "Removing #{self.class.english_name} '#{target}'"
-        raise CaskError, "Cannot remove undeletable #{self.class.english_name}." if MacOS.undeletable?(target)
+        raise CaskError, "Cannot remove undeletable #{self.class.english_name}." if undeletable?(target)
 
         return unless Utils.path_occupied?(target)
 
@@ -196,6 +196,10 @@ module Cask
           Utils.gain_permissions_remove(target, command:)
         end
       end
+
+      def undeletable?(target); end
     end
   end
 end
+
+require "extend/os/cask/artifact/moved"
diff --git a/Library/Homebrew/cask/config.rb b/Library/Homebrew/cask/config.rb
index ae8c2539fb..aa0d76dfb3 100644
--- a/Library/Homebrew/cask/config.rb
+++ b/Library/Homebrew/cask/config.rb
@@ -33,10 +33,10 @@ module Cask
       T::Hash[Symbol, String],
     )
 
-    sig { returns(T::Hash[Symbol, T.untyped]) }
+    sig { returns(T::Hash[Symbol, String]) }
     def self.defaults
       {
-        languages: LazyObject.new { MacOS.languages },
+        languages: LazyObject.new { ::OS::Mac.languages },
       }.merge(DEFAULT_DIRS).freeze
     end
 
@@ -223,3 +223,5 @@ module Cask
     end
   end
 end
+
+require "extend/os/cask/config"
diff --git a/Library/Homebrew/cask/installer.rb b/Library/Homebrew/cask/installer.rb
index f826211a8e..e9bbdc497d 100644
--- a/Library/Homebrew/cask/installer.rb
+++ b/Library/Homebrew/cask/installer.rb
@@ -76,6 +76,7 @@ module Cask
       satisfy_cask_and_formula_dependencies
     end
 
+    sig { void }
     def stage
       odebug "Cask::Installer#stage"
 
@@ -88,6 +89,7 @@ module Cask
       raise e
     end
 
+    sig { void }
     def install
       start_time = Time.now
       odebug "Cask::Installer#install"
@@ -152,6 +154,7 @@ on_request: true)
       end
     end
 
+    sig { void }
     def check_conflicts
       return unless @cask.conflicts_with
 
@@ -168,6 +171,7 @@ on_request: true)
       end
     end
 
+    sig { void }
     def uninstall_existing_cask
       return unless @cask.installed?
 
@@ -196,6 +200,7 @@ on_request: true)
                                           timeout:)
     end
 
+    sig { void }
     def verify_has_sha
       odebug "Checking cask has checksum"
       return if @cask.sha256 != :no_check
@@ -213,6 +218,12 @@ on_request: true)
       end
     end
 
+    sig { returns(ArtifactSet) }
+    def artifacts
+      @cask.artifacts
+    end
+
+    sig { params(to: Pathname).void }
     def extract_primary_container(to: @cask.staged_path)
       odebug "Extracting primary container"
 
@@ -242,7 +253,6 @@ on_request: true)
 
     sig { params(predecessor: T.nilable(Cask)).void }
     def install_artifacts(predecessor: nil)
-      artifacts = @cask.artifacts
       already_installed_artifacts = []
 
       odebug "Installing artifacts"
@@ -301,6 +311,7 @@ on_request: true)
       raise CaskError, @cask.depends_on.macos.message(type: :cask)
     end
 
+    sig { void }
     def check_arch_requirements
       return if @cask.depends_on.arch.nil?
 
@@ -316,6 +327,7 @@ on_request: true)
             "but you are running #{@current_arch}."
     end
 
+    sig { returns(T::Array[T.untyped]) }
     def cask_and_formula_dependencies
       return @cask_and_formula_dependencies if @cask_and_formula_dependencies
 
@@ -489,8 +501,6 @@ on_request: true)
 
     sig { params(clear: T::Boolean, successor: T.nilable(Cask)).void }
     def uninstall_artifacts(clear: false, successor: nil)
-      artifacts = @cask.artifacts
-
       odebug "Uninstalling artifacts"
       odebug "#{::Utils.pluralize("artifact", artifacts.length, include_count: true)} defined", artifacts
 
diff --git a/Library/Homebrew/cask/quarantine.rb b/Library/Homebrew/cask/quarantine.rb
index 4a36a5128e..ae680b0d23 100644
--- a/Library/Homebrew/cask/quarantine.rb
+++ b/Library/Homebrew/cask/quarantine.rb
@@ -266,3 +266,5 @@ module Cask
     end
   end
 end
+
+require "extend/os/cask/quarantine"
diff --git a/Library/Homebrew/extend/os/cask/artifact/moved.rb b/Library/Homebrew/extend/os/cask/artifact/moved.rb
new file mode 100644
index 0000000000..98d49e5904
--- /dev/null
+++ b/Library/Homebrew/extend/os/cask/artifact/moved.rb
@@ -0,0 +1,5 @@
+# typed: strict
+# frozen_string_literal: true
+
+require "extend/os/mac/cask/artifact/moved" if OS.mac?
+require "extend/os/linux/cask/artifact/moved" if OS.linux?
diff --git a/Library/Homebrew/extend/os/cask/config.rb b/Library/Homebrew/extend/os/cask/config.rb
new file mode 100644
index 0000000000..cc7f21e1bd
--- /dev/null
+++ b/Library/Homebrew/extend/os/cask/config.rb
@@ -0,0 +1,4 @@
+# typed: strict
+# frozen_string_literal: true
+
+require "extend/os/linux/cask/config" if OS.linux?
diff --git a/Library/Homebrew/extend/os/cask/quarantine.rb b/Library/Homebrew/extend/os/cask/quarantine.rb
new file mode 100644
index 0000000000..31671b65e5
--- /dev/null
+++ b/Library/Homebrew/extend/os/cask/quarantine.rb
@@ -0,0 +1,4 @@
+# typed: strict
+# frozen_string_literal: true
+
+require "extend/os/linux/cask/quarantine" if OS.linux?
diff --git a/Library/Homebrew/extend/os/linux/cask/artifact/moved.rb b/Library/Homebrew/extend/os/linux/cask/artifact/moved.rb
new file mode 100644
index 0000000000..3f6c420b47
--- /dev/null
+++ b/Library/Homebrew/extend/os/linux/cask/artifact/moved.rb
@@ -0,0 +1,23 @@
+# typed: strict
+# frozen_string_literal: true
+
+module OS
+  module Linux
+    module Cask
+      module Artifact
+        module Moved
+          extend T::Helpers
+
+          requires_ancestor { ::Cask::Artifact::Moved }
+
+          sig { params(target: Pathname).returns(T::Boolean) }
+          def undeletable?(target)
+            !target.parent.writable?
+          end
+        end
+      end
+    end
+  end
+end
+
+Cask::Artifact::Moved.prepend(OS::Linux::Cask::Config)
diff --git a/Library/Homebrew/extend/os/linux/cask/config.rb b/Library/Homebrew/extend/os/linux/cask/config.rb
new file mode 100644
index 0000000000..756cc7bae1
--- /dev/null
+++ b/Library/Homebrew/extend/os/linux/cask/config.rb
@@ -0,0 +1,30 @@
+# typed: strict
+# frozen_string_literal: true
+
+require "os/linux"
+
+module OS
+  module Linux
+    module Cask
+      module Config
+        module ClassMethods
+          DEFAULT_DIRS = T.let({
+            vst_plugindir:  "~/.vst",
+            vst3_plugindir: "~/.vst3",
+            fontdir:        "#{ENV.fetch("XDG_DATA_HOME", "~/.local/share")}/fonts",
+            appdir:         "~/.config/apps",
+          }.freeze, T::Hash[Symbol, String])
+
+          sig { returns(T::Hash[Symbol, String]) }
+          def defaults
+            {
+              languages: LazyObject.new { Linux.languages },
+            }.merge(DEFAULT_DIRS).freeze
+          end
+        end
+      end
+    end
+  end
+end
+
+Cask::Config.singleton_class.prepend(OS::Linux::Cask::Config::ClassMethods)
diff --git a/Library/Homebrew/extend/os/linux/cask/installer.rb b/Library/Homebrew/extend/os/linux/cask/installer.rb
index 536a08b1f5..76ac45eb7f 100644
--- a/Library/Homebrew/extend/os/linux/cask/installer.rb
+++ b/Library/Homebrew/extend/os/linux/cask/installer.rb
@@ -13,6 +13,8 @@ module OS
 
         sig { void }
         def check_stanza_os_requirements
+          return if artifacts.all?(::Cask::Artifact::Font)
+
           raise ::Cask::CaskError, "macOS is required for this software."
         end
       end
diff --git a/Library/Homebrew/extend/os/linux/cask/quarantine.rb b/Library/Homebrew/extend/os/linux/cask/quarantine.rb
new file mode 100644
index 0000000000..62d981ee3d
--- /dev/null
+++ b/Library/Homebrew/extend/os/linux/cask/quarantine.rb
@@ -0,0 +1,22 @@
+# typed: strict
+# frozen_string_literal: true
+
+module OS
+  module Linux
+    module Cask
+      module Quarantine
+        extend T::Helpers
+
+        requires_ancestor { ::Cask::Quarantine }
+
+        sig { returns(Symbol) }
+        def self.check_quarantine_support = :linux
+
+        sig { returns(T::Boolean) }
+        def self.available? = false
+      end
+    end
+  end
+end
+
+Cask::Quarantine.prepend(OS::Linux::Cask::Quarantine)
diff --git a/Library/Homebrew/extend/os/mac/cask/artifact/moved.rb b/Library/Homebrew/extend/os/mac/cask/artifact/moved.rb
new file mode 100644
index 0000000000..700557e564
--- /dev/null
+++ b/Library/Homebrew/extend/os/mac/cask/artifact/moved.rb
@@ -0,0 +1,25 @@
+# typed: strict
+# frozen_string_literal: true
+
+require "cask/macos"
+
+module OS
+  module Mac
+    module Cask
+      module Artifact
+        module Moved
+          extend T::Helpers
+
+          requires_ancestor { ::Cask::Artifact::Moved }
+
+          sig { params(target: Pathname).returns(T::Boolean) }
+          def undeletable?(target)
+            MacOS.undeletable?(target)
+          end
+        end
+      end
+    end
+  end
+end
+
+Cask::Artifact::Moved.prepend(OS::Mac::Cask::Artifact::Moved)
diff --git a/Library/Homebrew/extend/os/mac/readall.rb b/Library/Homebrew/extend/os/mac/readall.rb
index 853654a24e..23f71e403c 100644
--- a/Library/Homebrew/extend/os/mac/readall.rb
+++ b/Library/Homebrew/extend/os/mac/readall.rb
@@ -20,7 +20,7 @@ module OS
 
         success = T.let(true, T::Boolean)
         tap.cask_files.each do |file|
-          cask = Cask::CaskLoader.load(file)
+          cask = ::Cask::CaskLoader.load(file)
 
           # Fine to have missing URLs for unsupported macOS
           macos_req = cask.depends_on.macos
diff --git a/Library/Homebrew/os/linux.rb b/Library/Homebrew/os/linux.rb
index e8f4832843..4345e9a1f1 100644
--- a/Library/Homebrew/os/linux.rb
+++ b/Library/Homebrew/os/linux.rb
@@ -13,6 +13,8 @@ module OS
     raise "Loaded OS::Linux on macOS!" if OS.mac?
     # rubocop:enable Homebrew/MoveToExtendOS
 
+    @languages = T.let([], T::Array[String])
+
     # Get the OS version.
     #
     # @api internal
@@ -56,5 +58,15 @@ module OS
         Version::NULL
       end
     end
+
+    sig { returns(T::Array[String]) }
+    def self.languages
+      return @languages if @languages.present?
+
+      os_langs = Utils.popen_read("localectl", "list-locales")
+      os_langs = os_langs.scan(/[^ \n"(),]+/).map { |item| item.split(".").first.tr("_", "-") }
+
+      @languages = os_langs
+    end
   end
 end
diff --git a/Library/Homebrew/os/mac.rb b/Library/Homebrew/os/mac.rb
index dbb3ef6463..c59bb0e50c 100644
--- a/Library/Homebrew/os/mac.rb
+++ b/Library/Homebrew/os/mac.rb
@@ -69,6 +69,7 @@ module OS
       end
     end
 
+    sig { returns(T::Array[String]) }
     def self.languages
       return @languages if @languages