

My os does not do that
I don’t consider “wanting a secure app to be installed through first party means” to be particularly unusual. I know in Linux it’s standard to just install random stuff from the internet with root. I’ve obviously done that myself, but for secure stuff I want first party. Making a flatpak wouldn’t be hard (they probably just need to review someone else’s work – it’s like an intern project)
Having windows on top of each other might be useless but it also doesn’t hurt anything, and KDE already has the ability to snap windows into different positions. So this description doesn’t really capture the problem you’re solving.