No, they're not a feature from X, quite the opposite. They're Wayland only.
If the hardware works, you might want to check sudo libinput debug-events for whether or not the driver works as well. If it does report gesture events with 3 and 4 fingers and KWin doesn't react to them, please open a bug report at bugs.kde.org about it
KWin had four finger touchpad gestures since 2017. If they don't work for you in the Wayland session, your touchpad most likely simply doesn't support detecting more than two fingers
Even finding a decent and working FTP/SFTP/FTPS desktop client (similar WinSCP or Cyberduck) is an impossible task as there a few, but they all fail even at basic stuff like dragging and dropping a file.
Of course you'll have trouble finding a dedicated desktop client... that functionality is literally built into most Linux file managers.
All it ever was intended for was to make us feel like something was being done while doing absolutely nothing.
It certainly does help a little bit. But it's of course still not a coincidence that companies are pushing for it instead of more effective measures... It's not just cheap but it also pushes people to believe that measures to save the environment are all useless and annoying, and makes them less likely to want more to happen.
While I agree with your conclusion, your explanation is not right.
X11 is the 11th version of the X protocol, it is not an implementation. The Xorg server is the only relevant implementation for the server side of things, and for X11 window managers and X11 compositors there's only libx11 (which is very horrible) or libxcb (slightly less horrible). Both of those are about as high level as libwayland-server + libwayland-scanner - which is to say, nearly as low level as it gets.
wlroots in contrast provides comparatively high level libraries / components, which make the implementation of compositors less of a headache than having to mess around with barely documented xcb functions.
SteamVR in Flatpak functions but you will get rediced performance because it can't set CAP_SYS_NICE for vrcompositor. I haven't checked if setting it manually could work though
I don't know how to configure libinput under ${YOUR_FAVORITE_COMPOSITOR}, you'll have to figure that out yourself. In Plasma it's simply in the touchpad settings
That sounds like your TV is temporarily disconnecting at random, or at least doing something that the GPU detects as a disconnect.
Most likely, AMD's hotplug detection is too aggressive. You can report that at https://gitlab.freedesktop.org/drm/amd/-/issues