I've been testing O.B.O.L regularly on Steam Deck, and believe the game is 100% compatible, and plays fantastic on the device! I have a native linux build to ensure the best compatibility possible.
You can play using the touchscreen, mouse only or dpad for camera navigation and trackpad for mouse emulation.
Please use the comments on this event to let me know your experience with the game on Steam Deck.
Cheers,
Eliptik