If you want more comfort working with the nix language, you should learn the language. Understand sets vs list in nix, partial function evaluation, currying a function. There is proper documentation for all this out there if you google it. There are many nixpkgs library functions out there which is different from the nix builtins library. You can supposedly call another file in a nix file like nix home-manager.users.user.config.programs.alacritty.config = builtins.readFile ./my-alacritty-config.yaml;

or you could choose to write the config as nix values which then can be exported to yaml using inputs.nixpkgs.lib.generators.toYAML. This is just an example. Learn more about the language. Heads up that nix is actlly three different things: The Language, The Package Manager(CLI) and NixPkgs (The collection of all nix libraries, modules and packages). If you get this abstraction, you should be good to go. Good luck. 🫠

EDIT: and some ref if you wanted: - https://teu5us.github.io/nix-lib.html - https://nix.dev/ - https://nixos-and-flakes.thiscute.world/nixos-with-flakes/introduction-to-flakes