On which Desktop Environment/wayland compositor? I am pretty sure Firefox Picture in picture works as intented (tiny window, stays on top of things) on GNOME's

On which Desktop Environment/wayland compositor? I am pretty sure Firefox Picture in picture works as intented (tiny window, stays on top of things) on GNOME's wayland session, and on Plasma 5.27.x I was able to make it work with a few KWin rules set by GUI (I would love to share the details, but I don't have my Plasma machine with me currently).