I want to package the Arc Firefox Theme, which complements the Arc Theme for desktop environments based on GTK. It is a set of three extensions for Firefox (*.xpi files) that should be installed into the Firefox extensions directory (${firefox-unwrapped}/lib/firefox-xx.x.x/browser/extensions/ I think).

Since the store is read-only, that can not be done directly. Therefore a means of installing Firefox extensions should be created in NixOS.

Would it be feasible to have a directory /run/current-system/sw/share/firefox/extensions containing symbolic links to installed extensions (*.xpi files), and make ${firefox-unwrapped}/lib/firefox-xx.x.x/browser/extensions be a symbolic link to it?