A tablet isn’t set up to act as a display for another device. Any solution you find is going to have to involve software running on the tablet to decode and display the video stream, which is going to add significant lag. You’d be better off buying a small monitor. Something like this: https://a.co/d/2hmCX3q
One of my favorite in-person MP games of all time is Towerfall Ascension. My family and I used to spend so much time laughing out loud while playing that game. So many ridiculous trick shots with all the power ups. I haven’t tried it on Steam Deck, but I don’t see any reason why it wouldn’t work, assuming you can get multiple controllers connected.
Have you tried Tabletop Simulator?