Unfortunately, the security updates introduced in MacOS Catalina have made installing Nix on the latest version of MacOS a fairly involved process.[1] I looked at using it when I rebuilt my computer recently and decided to wait until it was more baked.
[1] Catalina restricts which directories can be added to the root dir. Nix uses /nix.
[1] Catalina restricts which directories can be added to the root dir. Nix uses /nix.