Since when I started the thread, I’ve migrated my setup to use nix itself aswell. My current configuration is here: https://github.com/pinpox/nixos-home/blob/58dc8cba602fe6298e7f8802d9d542fea9ece432/modules/shell.nix#L109-L152
I manage my machine’s configuration and my home-manager configs with flakes, so I will be replacing that builtins.fetchGit lines with flake and have the management and updates be done via the flake.lock file.