I ended up working this out. For anyone viewing this ticket in the future, do the following:
- Add
nixpkgs-unstable.url = "github:NixOS/nixpkgs/nixos-unstable";to one’sinputs - Add
nixos-unstableto the arguments ofoutputs. - Pass
nixos-unstableto anyimportstatements below where you need it. - Add
nixos-unstableto the argument list of any imported files where you have added thenixos-unstableargument.
That will then generate an entry in flake.nix the next time you run things. You can then manually edit the commit pin if you like.