I regularly do remote VNC and X11 access on stuff like raspberry pi zero and in these cases GPU does not work, you won't be able to open a GL context at all. Also whenever i upadte my kernel on archlinux i'm not able to open a gl context until i reboot, so I really need apps that don't need a gpu context just to show stuff
But I seem to recall there are dirt cheap hacks to do same. I may be conflating it with "resister jammed into DVI port" which worked back in the VGA and DVI days. Memory unlocked - did this to an old Mac Mini in a closet for some reason.