Some day it will make it's way to banking apps/sites being unusable on OSes other than approved "secure" ones.
That day was years ago. Many banking apps refuse to start if you even just have your bootloader unlocked, and some banking websites only support Chrome, some really crappy ones even only Chrome or Edge on Windows specifically.
The real one? It was fine on Xorg though
When an app (in your case, Steam) uses X11 APIs to move the cursor, that of course works on Xorg, but Xwayland merely emulates it - so it moves the X11 pointer for X11 apps, but not the pointer from the Wayland compositor.
Some compositors allow Xwayland to request moving the real pointer instead of doing emulation, but River apparently doesn't.
I have some problems with X11 cursors and that's quite normal with Wayland obviously
It's not. There is no Wayland specific cursor format, it's all just images on disk, and the most widely used format hasn't changed away from Xcursors yet.
For example, my cursor can become invisible if my screen sleeps
That's either a compositor or driver bug, please report it (as I've never seen that on Plasma, to your compositor first).
Additional controllers that control mouse cursor don't control X11 cursor, however they still work, I just don't know where the cursor is unless it highlights something.
That's because it moves the X11 pointer but not the real one. A cursor theme can't change that.
If the KVM tells the PC that the TV has been disconnected, then you can just disable the other screens in the display settings while the TV is connected, and it'll just work. Which screens are enabled or disabled is remembered depending on the currently connected displays.
That's because Windows has a system provided toolkit that most apps use
long press for imitating a right click, but text selection with popup copy/paste/etc buttons would also be useful.
Unfortunately that's not something that can be done system wide, apps have to handle that themselves.
afaik not packaged for any distro
It's packaged in every widely used distro.
Then you're using Xorg, not Wayland.
What problems do you have with per screen scaling on Wayland?
Stop using Xorg and your scaling problems are gone.
Debian
... is not something you should ever use on a desktop PC. Due to its eternally very outdated nature and not even shipping bugfix updates**** it is not a good fit for anything but servers.
Wayland, for some reason, couldn't handle 4 monitors, with one above the other three.
"Wayland" doesn't handle monitors at all. What (because of Debian, wildly outdated) desktop did you use?
Oh, and the biggest issue I had with Windows was copied straight into Linux. I want my (single) taskbar on a monitor that isn't my primary.
Not a Linux issue, but a problem with the desktop environment you chose. KDE Plasma allows you to configure panels in any way you want.
and
Why the fuck do people upvote this misinformation? They held primaries literally this year, which is information everyone can trivially look up