> we should be able to disable shipping Nix entirely, by setting nix.enable = false.

It was at this point I began to question the entire exercise. If you don't want nix to even be installed, do you really want NixOS at all?

It would probably be much simpler to just build an image from scratch with the packages you want, composed in the way you want them, rather than contort the NixOS "UX" to produce the image you want.

Nah this kind of thing is pretty common for servers or little embedded computers. If you're always building the image on some other machine, there's no compelling reason to include that binary or it's dependency closure on the system.

Typically someone who goes for this indeed likes and runs "full fat" NixOS on some systems. What they want is to get really small images for some special purpose, like containers or disk images for a puny old Raspberry Pi, and build them using their usual NixOS workstation or server or whatever.

> build an image from scratch with the packages you want

Using what? Using NixOS to configure a system is orthogonal to the system actually running the Nix binary. Nix/Nixpkgs provide well maintained package derivations and module configuration for the largest amount of software of any ecosystem. IMO it's far simpler than Yocto or Buildroot or the dozen OCI container builder ecosystems that go in and out of favor.