Pop Shell can actually be used on other distros. Here's how: https://support.system76.com/articles/pop-shell/

[...] but I don’t want a Windows clone, [...]

KDE fortunately doesn't have to be a Windows clone. There are several guides available on how to customize the UX / workflow to something completely different. I get what you mean, though, the default UX seems to be at least inspired by Windows.

This is purely anecdotal evidence, but on my 2013 ThinkPad X220 (dual-core i5, 12GB RAM) Plasma "feels" snappier and more responsive than GNOME.

Also the fps on my Nvidia graphics card is really bad in games.

Are you sure you have the official Nvidia driver installed? Most Linux distros, if not explicitly configured otherwise*, use the open source "nouveau" driver by default. Since that driver doesn't support some vital aspects - such as frequency scaling - of the hardware, the performance is bad.

*Some distros, like Pop! OS and EndeavourOS, offer a "Nvidia install", meaning that the official driver will be installed and configured upon OS installation.

Except of course with Nvidia drivers, those are always shit.

Doesn't that depend on the distro? In most cases they should be supplied as a (meta)package and only require installation through the package manager, kernel modules should be built automatically then.

While this is ofc only anecdotal evidence: I haven't had problems with different models of Nvidia GPUs on different distributions (OpenSUSE, Debian, Pop!_OS, Elementary, EndeavourOS) in the last years. With a small workaround, even Wayland works flawlessly - the problem with missing GAMMA_LUT support and night light notwithstanding here.

Reads a bit like projection on the responder's part, don't worry.

Yeah, you're probably right. Haven't had any issues the last time I used Manjaro, though. But that's only anecdotal evidence at best.

+1 for EndeavourOS. Just installed it on an older notebook (ThinkPad X220) and damn, was it a breeze to set up properly.