In reply to @shortcutz:matrix.org

actually if it builds fine for you it is probably how i am using it in my configuration- i have a member of inputscalled gnomeNixpkgs in my system flake.nix pointing to github:NixOS/nixpkgs/gnome, and then in my modules i've added:

{
  nixpkgs.overlays = [
    (self: super: {
      gnome = gnomeNixpkgs.legacyPackages.x86_64-linux.gnome;
    })
  ];
}