@Takiro I agree. Wayland has a lot to offer (eg. on my Lenovo Yoga, the touch gesture and interaction with Dolphin, palm rejection, the on screen keyboard, etc...everything is better under Wayland in this aspect).
About Plasma 6 on X11, I learned only after publishing that it still had the kcm_wacom . That's an information who never came to me, even with a lot of research on the topic. I'm glad it exists!
I will amend the Plasma 6 section of my article with this info, for completion.