What exactly is an OS to you? All distros are operating systems because they ship all the tools and utilities need for the system to function (on top of a package manager).

The fact that the KDE devs didn't write that code themselves doesn't disqualify it from being an OS.

KDE neon is what they're selling

Have you tried manually installing it?

So you’re asking people what they do for a living?

Doing something for 8 hours a day, 40 hours a week makes you a lot better at that thing than other people.