FYI you can do:

nixos-rebuild switch --flake git+https://yourgithost.com/yourrepo

I’ve only been using it for about a year, but as of now I can’t imagine ever going back to imperative system configuration. Having my infrastructure declared in its entirety by a version controlled code base is just too comfy.

Lemmy is packaged already, and you can find configuration options here.

kbin is not packaged yet, thus there are no configuration options for it.

There currently is an open issue requesting it to be packaged here.