Ah, for some reason I figured this was a minor bug that'd be fixed eventually. Wayland windows are never allowed to spawn always-on-top? Sort of lame.

If the logic is that it's the window manager's job to set window rules for this, fine, but in that case Plasma should probably ship with preconfigured rules matching the Chrome/Firefox PiP window.

I also find the lack of an Xlib-compatible macro API disruptive but I usually run an X11 session inside Xvnc for this purpose anyway.