> Actually, last time I looked at NixOS, you could also install things the imperative way, but that's a silly thing to do.

Actually not, because if you do, you will find these changes added to a file declaratively describing all the changes you have committed to the system (or user-context) as a whole.

It's a good way to build a config if you're not fully comfortable with nix-syntax.

I don't remember where the file ends up, but it is there.