[maxxk]

I know of least three approaches:

1. For per-user configuration there is home-manager which symlinks dotfiles to Nix store based on a single "home.nix" derivation (state). Home-manager is usable outside of NixOS and, in my opinion, it is better than most dotfiles managers. https://github.com/nix-community/home-manager

2. In NixOS /etc is composed in the same way from the system derivation.

3. Outside of NixOS, I think, one can build systemd units which refer directly to configuration files in Nix store. Probably one can add config paths into wrappers, but it will be very fragile and won't scale.