Don't worry
ps -H -t /dev/tty1
Would still give you the display server's pid which you can kill with the command provided however I don't know how to restart the wayland display server after that. So you would have to look into that.
My advice though would still remain the same. Try with less destructive plasmashell first and move to kwin if it doesn't work.
Since you too are using kde plasma the plasmashell command should remain same. Just the kwin one should change to.
setsid kwin_wayland --replace &