Gang Beasts, Most to all of The Jackbox Party packs (family-friendly options in settings), Plate Up!, and Stick Fight The Game are all near the top of my list with my family.

In the settings of MHW --> adjust the resolution to 1280x720 and set the screen mode as “full screen”. Restart, and then use the “…” button on your steam deck and adjust the Scaling Mode (in the “battery” section) to stretch.