Right now nix flake check checks sanity of a lot of common flake attributes, but it fails to consider that there are tools that might extend flakes' usability beyond what Nix and NixOS offers - e.g. home-manager. Currently in my personal flake (https://gitlab.com/vikanezrimaya/nix-flake) I use homeManagerModules and homeManagerConfigurations as additional flake outputs for home-manager and an attribute called activationPackage, that for every machine deploys a NixOS configuration and my personal home-manager config. Nix warns me of existence of these attributes as if they're typos. I'd like to somehow extend Nix (maybe with a plugin somehow embedded in a flake?) that will type-check all of the custom attributes I designed.