I use KDE. Some use GNOME. Most other options are probably to be left out as X11 is unsafe.
Cosmic is not nearly finished, but will probably be a bit safer, as its in rust, even though not tested.
Then there are window managers like Sway, Hyprland, waymonad, wayfire, etc.
RaspberryPi also has their own Wayland Desktop.
Is every Wayland Desktop / WM equally safe, what are other variables here like language, features, control over permissions, etc?
This isn’t really true. Run
libinput debug-events
. In most distros users will have access to run this and keylog all input events.I use Wayland and love it, but keyloggers are not prevented on most common setups.