Here is an example how an installer can look with many customisation options: RFC: Graphical installer for NixOS · Issue #21662 · NixOS/nixpkgs · GitHub
I would love to use the solid foundation of NixOS with the user-friendly desktop from elementary OS. Many components are still missing sadly.
We would have to research a way to organize the options NixOS has without overwhelming the user. Maybe that could be a topic for a master thesis? Also sane defaults for desktop users.
A major part would be to install and update Nix packages with a graphical tool. With PackageKit support, we are not far away from that. Packagekit not compiling with Nix-backend enabled · Issue #21230 · NixOS/nixpkgs · GitHub We also need a graphical way to do a system upgrade.
Localization would also help reach more users.
I think the goal should be to make NixOS as user-friendy as possible without loosing flexibillity for advanced users. But an own “distro” with install image and manual could be a good start to experiment and get feedback.