You would most lilely be looking at a Kodi setup.
Look up LibreElec, super simple all in one image, kodi has a ton of plugins for everything you’d need. You’ll probably need to add some extra repos to get everything you want, but it’s all pretty easy to figure out with searches
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.