Your link for Myne is a fork that hasn’t been updated in a long time. I haven’t used it but you might want to check you were using the right version

Considering all of the PC handhelds being released, 1080p is the best you can really do on a handheld screen with modernish games. Steam Deck is the most successful and it is only 800p. Having a 1440 or 2160 screen would decimate battery with little to no benefit.