> > 3. We need a desktop environment that's visually appealing and has a good UX.
> Such as KDE and the rest?
Just personal taste, but I don't find KDE visually appealing, and not only the default theme ("Breeze"). Unfortunately, I can't get used to the usability issues on GNOME.
IMO, the sweet spot of visually appealing and good UX is .... Windows 10 (sigh), followed by a close second in Cinnamon (and I'm also a fan of IceWM).
Consider checking out nixos. Although this is already possible to do in normal distros.
> The OS should define a stable format for the OS to install, update and uninstall these files
Like .deb and .rpm?
> 3. We need a desktop environment that's visually appealing and has a good UX.
Such as KDE and the rest?
> We need centralized, thorough and official user documentation about the OS
Distros have their own documentation already.
> And this documentation should be distinct from the developer's documentation
Why?
> The user shouldn't need to learn 10 different config file formats
You will love nixos then.