Steam Deck + Capture Card
See my blog post here: https://kevbot.xyz/blog/streaming-melee-on-deck/
Nowadays I do this setup for my side streams (example), but I replace the Steam Deck with my laptop. This has a few advantages over a Steam Deck:
- I have an actual computer with a built in keyboard and touchpad.
- A builtin webcam used in conjunction with a USB webcam, each pointed at the players.
- A larger screen to see what's going on.