I agree that the current Gnome experience is pretty bad, but I think the solution rather than removing it entirely is to add calamares to guide the user through an installation.
I’ve been recently trying to fix calamares on NixOS to hopefully fix this. I made a proof on concept ISO here (Also above 2Gb though. Not sure if it’d even be possible to optimize it below). Some form of templates or flavors in nixos-generate-config could definitely help though, and would be able to be integrated into the calamares modules I’m working on.
I think an ideal solution would be to boot directly to a DE, whether that be Gnome or Plasma, and launch calamares, where the user could pick which desktop environment to install, by default whichever shipped with the ISO. I haven’t had a chance to work on that recently, since busy with studies, but I also agree that currently, the Gnome UX on NixOS is not ideal. Another project I’m working on is a dconf-editor esq app similar to nix-gui but instead using a tool I made, nix-editor to modify the AST directly, hopefully leading to more stability. Hopefully with this, users fresh off a calamares install can be guided and taught nix syntax.
But for now, I think the best solution to this would be to add calamares to both the Gnome and Plasma ISO, that way new users can at least install NixOS with ease, even if having to learn more afterward is harder.