Interplay Entertainment along with Square One Games and Black Isle Studios have confirmed that Baldur's Gate: Dark Alliance II is coming to Steam along with Native Linux support.
This follows along from Baldur's Gate: Dark Alliance that had a Steam release last year that also had Native Linux support and it will work nicely on the Steam Deck too.
From the Steam page:
Unspeakable evil has returned to the legendary city of Baldur's Gate in this dungeon-crawling, action RPG fantasy classic. A call for adventurers echoes through the embattled land. Cunning warriors and bold magic users are desperately needed to reclaim Baldur's Gate from a dark sorcery that threatens all in its path.
- Five new heroes with new class feats and abilities
- Hack your way or cast powerful spells through over 80 perilous levels
- Hidden areas, secret characters, and hundreds of items to discover, customize, and use
- Forge unique magical weapons and armor to maximize the damage you inflict in battle
- Conquer hordes of beasts and armies of Hobgoblins, Ghouls, Golems and dreaded Dragons
- Compelling single or two-player cooperative modes of play
Additionally, they previously teased a rough video of it running on a Steam Deck:
You can wishlist / follow on Steam. Quick update: GOG confirmed too but no store page yet.