I've tried the wayland session again in Plasma 5.10.2 but unfortunately, it's still unusable, so I'll start to report the various bugs to see if I can help debug them. The main bug is that the whole system freeze when I logout. At that point, I need to turn off the notebook by pressing the power button. The freeze happened also at other random instants when I was not doing anything in particular. Is it there some log that I can report?
*** This bug has been marked as a duplicate of bug 372789 ***