List of Firefox add-on packages to install for this profile. Some pre-packaged add-ons are accessible from the Nix User Repository. Once you have NUR installed run
$ nix-env -f '<nixpkgs>' -qaP -A nur.repos.rycee.firefox-addons
to list the available Firefox add-ons.
Note that it is necessary to manually enable these extensions inside Firefox after the first installation.