Used nix last year but dropped it after home-manager decided to unlink the apps from the Applications directory.
How is the current situation on usability of nix-Darwin + home-manager + brew?
Packages still fails to get indexed correctly in spotlight? I really like a fully repro environment but the fact that the usu ability was low bothered me a lot.
I use nix-darwin + home-manager (with a sprinkle of homebrew) as my daily use dotfiles config for home and work, and have for the least year or so. It works great, after some initial growing pains.
There is a trivial fix for spotlight which makes it work correctly. You can view it here: https://github.com/natecox/dotfiles/blob/3c9b493afd893c0ebd0a355b81ad81f99fcfcdf2/modules/home-manager/default.nix#L40