From my experience, multiple crashes in GPU usually indicate insufficient power when power demand is high (When a game is running).
This is usually handled by the PMU to prevent power spikes that cause these crashes.
May I make a suggestion, try getting another power adapter, preferably an Apple iPad adapter, those are very reliable, and hook that up to your GPD Win, wait for 5 minutes while the device is switched off, then turn it on, and run your games, see if you if still suffer from GPU crashes now ?