I have put 46 hours into BG3 exclusively on my Steam Deck. It is installed on the SD card, and I have the game limited to 24fps per a guide that was posted somewhere. I have various decky mods and adjustments from setting up ToTK on yuzu, which included using powertools and making adjustments to BIOS (swap file size increase maybe?)
I am nearing the end of act 1 and the only issues I’ve had are audio related after waking the deck up from sleep. I typically leave the game running and rarely close it completely.
My deck is running the main stable build, and I have the game running with the default proton build, not experimental. Playing with the most popular community Kb&M controller setup listed.
I hope you can figure out how to get it running, because It’s such a good game. Good luck
Theirs and mine both