@ebassi I don't use Gnome and I'm still in #X11 land on #OpenBSD and my #MLVWM window manager, so I'm just "thinking out loud" here...

Do Gnome apps reliably "do the right thing" if sent a SIGTERM, e.g. confirming quit and/or prompting to save unsave changes, as necessary? If so, maybe write a script (triggered on super-q) to get the PID for the frontmost window's process and then `kill -TERM -p $PID` it?