user-defined home.nix template

[cem2ran]

First of all, thank you for creating this project! 🙏

Is your feature request related to a problem? Please describe.
I'm trying to figure out how to add home-brew packages and mas apps as is possible in home-manager. Example:
https:/dustinlyons/nixos-config/blob/073fac3baaccbedfa4de4c196f611f1e0d27b4f0/modules/darwin/home-manager.nix#L39-L46

I don't think this is supported via fleek.yaml but also it seems not possible to modify home.nix as it will be overridden?

Describe the solution you'd like
Would it be possible to specify nix files to merge into the generated home.nix or specify as a template? Then I would be able to also configure all the other options available in home-manager

[cem2ran]

I realize there's some overlap with the following issue #325, and it would be great to have a fleek brew add "package" or even flake mas add "app", that being said I'd still like to configure my machine through home-manager. Would be great to do this without having to opt out of fleek.

[cem2ran]

Perhaps its possible to extend home-manager via user.nix, but I just don't know enough nix 🥲