Yes I know its not this, but same approach, I can browse my steam library on my phone and then play a game, while my PC runs it and does all the work.. Something like dead by daylight might be possible, it needs minimal keys 😀

Tested this morning. Played Path of Exile, Terraria and killing Floor 2. Screen size and cropping can get quite buggy if you use touch instead of KB+Mouse. As there is zoom function. Connecting to system with more screens is not best idea either. KB works fine, mouse has only left button (android standard). Mouse cursor is separated, one is local shown on screen, and another is one on steam/game hosting system. So, you have to distinct between local ghost and real mouse on target server as they may be in different location. Did not try gamepad yet. Video compression may cause some visual bugs. Tried limitation to 5Mbps and it was OK on 1080p. Still did not test it via VPN.