this monitor seems to be decent and can be powered with a battery bank through a usb-c cable. https://www.amazon.com/dp/B0711K8YJW/?coliid=I1PDQLWSQNF4P&colid=26X5SU2BD89C9&psc=1&ref_=lv_ov_lig_dp_it#customerReviews

i don't actually own it but i was thinking of buying one. the reviews are decent with some ppl commenting that it works well for a retropie setup, which probably means it should be good for a snes too.