Without reading the article: I've used Nix on macOS without nix-darwin or home-manager for some time now. I define my packages in a flake.nix that exports an environment and I use install using `nix profile`.
That's a great setup for package management. Stuff like Nix-Darwin and Home Manager start to shine when you want to also do some configuration management. For just package management, your approach is probably better in that it's simpler.
