I've been using Nix on macOS for almost a year. The good (and bad) thing about Nix is that it supports many different use cases, so you have to spend some time understanding the options before you can even figure out which flavor to install.

A good way to get started is to start using Nix to replace/supplement Homebrew. You can install Nix in addition to Homebrew and have some packages installed by one and some by the other. You can uninstall a Homebrew package and then reinstall it with Nix. You can even remove it with Nix and go back to Homebrew if you like.

I would generally recommend the following:

1. Use the Determinate Systems Nix installer, see https://zero-to-nix.com/start/install

2. Use "Flakes" (unfortunately the core documentation isn't updated for flakes)

3. Use "Home Manger" -- I would recommend the Flakes-based "Standalone setup": https://nix-community.github.io/home-manager/index.xhtml#sec...

I would wait on nix-darwin until you are sure you need/want it. (I have recently started using it for its support of the `linux-builder` feature, but not everyone needs that.)

As a software developer who uses macOS to develop for Linux, it is a great tool and I cautiously recommend it to those who are willing to deal with some learning curve and frustration.

I haven't yet used nix-darwin enough to make a recommendation one way or another. (But the `linux-builder` feature is compelling if you need it: https://nixcademy.com/posts/macos-linux-builder/)