Sure, but if you run the same Nix flake on two macOS machines with the same architecture, it will have the same behavior. Most of package managers don't offer

Sure, but if you run the same Nix flake on two macOS machines with the same architecture, it will have the same behavior. Most of package managers don't offer that guarantee. Only Guix has a similar level of assurance? Nix openly recognizes outputs are different per platform, x86_64-linux is different from aarch64-darwin. Impossible not to, as ultimately architectures may behave differently.