This is my config for nix-darwin with home-manager which manages my macOS installation. I'm happy if you find some inspiration here but be aware this is early stage.
First install nix in "multi-user mode", for example via curl -L https://nixos.org/nix/install | sh -s -- --daemon --darwin-use-unencrypted-nix-store-volume (see nix multi-user mode and macOS install guide). Then install nix-darwin and home-manager. After that you can deploy the configuration like this:
cd ~/.nixpkgs
git clone git@github.com:phlmn/nix-darwin-config.git
nix-darwin rebuild