> My second issue is that the files clearly aren't machine-editable. There's no sensible way to make a GUI that can edit your hostname if the hostname is define

> My second issue is that the files clearly aren't machine-editable. There's no sensible way to make a GUI that can edit your hostname if the hostname is defined in some Turing complete functional program. But you also don't need to! NixOS has a module system, with override/priority mechanics; so your GUI tool could just generate its own Nix file with its own settings, totally ignoring the system-wide settings, and then all you need to do is apply that generated configuration file in your imports; the module priority system does the rest.