Yes, this happens automatically for me when I launch games. I don’t remember doing anything special to set it up (Kubuntu with nVidia drivers on X11). I do mostly game in true full screen though, not “full screened window”

It does yes. Although it launches Steam directly as its own … “shelll”? Is that the right word? KDE is bypassed entirely unless you launch “Desktop Mode”

Anyways, I still wouldn’t recommend Arch to a new user, go with something easier and more mainstream for your first Linux experience. PopOS, Mint, Fedora, Norabora, Ubuntu/Kubuntu

Also, saying Steam Deck uses Arch isn’t wrong, but it’s a bit misleading. It uses an Arch base , curated, configured and tested by Valve, and finally periodically shipped as updates using immutable root images (on a single well defined hardware platform). If you install vanilla Arch yourself you’re responsible for all configuration and testing yourself.

Simply put, X11 is the bottom of the graphics stack, i.e. everything that makes Linux have more than just a command line has historically been built on top of X11

X11 is OLD. Like really old. And has a bunch of problem because of it (no variable refresh rate, no good multi monitor support, no proper fractional scaling , tearing, no security etc) It’s also very mature. Somehow developers have managed to build a decent user experience out of the old X11

The Wayland protocol was designed to overcome the shortcomings of X11 and replace it. Wayland is now at the cusp of being a fully functional complete replacement for X11. It already is for many (most?) use cases.

Many Applications that are not made for Wayland will still run in Wayland, but they run in a fake X11 server inside called Xwayland. But native Wayland is better (performance, security, features)

Wayland very good on AMD and Intel these days. Nvidia was unsupported, but last year nVidia made a business decision to support EGL(?) so with fresh drives work has begun in Gnome and KDE to support Nvidia in Wayland. I’m not sure how mature Nvidia on Wayland is yet