can vouch for the detsys installer, and anecdotally, the resulting nix install seems more resilient across os updates. on a similar note, nix-darwin is a must-have. the typical nix-env stuff you see in introductions to nix on non-nixos systems really sells it short, as it feels like just another package manager to keep track of. by contrast, nix-darwin brings the centralised configuration.nix approach, which makes it way harder to hose your environment.
https://github.com/LnL7/nix-darwin