If I use wayland, can I remove x11 xorg from my system kaOS?

No, not possible at this time, many applications still depend on xwayland to run.

    And forgot to mention, all is packaged right now so anyone can still choose to run Plasma 6 with X (older Nvidia cards for example, cannot use Wayland with non-free), so the Plasma desktop has hard depends on many xorg libraries & apps, that won't change until no-one needs to run the plasma_x11 option instead of (default) wayland.