Kingdom Come Deliverance. There definitely is a bar to entry with how steep the learning curve is.
Once past that, it’s probably one of the best immersive RPGs I’ve ever played. Bonus points if you’re a history buff and study European history in the late 1300s.
That being said, I can say this game isn’t for everyone
Well worth it given your use cases.
I’d definitely utilize Proton DB to figure out what games work well on the Steam Deck. The verified badge on steam doesn’t usually give an accurate assessment of what will play well on it.