I doubt a user wants or cares about any of that. User story:
As a User I want to select an application to run so that I can use the application.
This applies to practically everything, if you want to play a game, you don't want to dick around with installers, managers, layers, configurations etc. Just point and click, that's all it should need.
My main point was in the first paragraph. Users care about reliability and I was justifying why I think Nix has the potential to be a more reliable base for a GUI than other options.
I also do think certain users will care about e.g. extensibility/composabilty, as soon as they have to do anything outside of the officially blessed path. Having the ability to compose things nicely is pretty useful. It’s the difference between having to recreate the entire GUI configuration manually and just being able to dip into the config for the (likely small) non-standard part of the system.
While I agree with that, operating systems like macOS and Windows have shown that ease of use still beats other features when a user simply wants to 'do' something.
As good (or as bad) as the technical underpinnings can be, as long as the user gets what they want most of the time they are fine with it.
Nix is one big advantage of course and that is that is isn't a commercial endeavour beholden to markets and income. So it doesn't really matter what general users might want or think (at least not at this stage). We also still have the same problem that is always present and that is content availability. If a user wants to install a Netflix client but none is available, it doesn't matter how good the tools are. Even the best UX can't help when the desired content isn't available.
As a User I want to select an application to run so that I can use the application.
This applies to practically everything, if you want to play a game, you don't want to dick around with installers, managers, layers, configurations etc. Just point and click, that's all it should need.