The discover store comes with KDE nowadays. GNOME has a similar store. Most recommended distros will preinstall one of those two. Ubuntu has a similar snap store, I think.
I guess the steam flatpak is unofficial. Works, though. Very simple, lazy solution. Could have gone through the fedora repos, too, where they've gone through the effort of repacking the deb for their users.
Dunno what your package manager problem is. Don't even know what you're running. Mine works fine, and certainly better than the windows store 🤷
Appimages sure aren't recognized as system apps. They're basically like an exe on windows. I'd rather manually add my rare appimage to the menu than go through the installer hell windows has.
Your point seems a little silly because, honestly, my experience is that developers have largely made the Linux desktop experience so simple and stable that it works better than any windows machine I've used in the past decade. I'm sorry this hasn't been your experience, but in the last couple of years I've pretty much only needed to open the terminal because I want to, not because I need to.
Uh, I kind of assume you're trolling at this point since a) you got notably more unpleasant in a hurry, and b) if you think exes work the same way every time you have lived a weirdly blessed life.
I hope you sort out your package management problems sometime but this has clearly gotten unproductive. Cheers!