All above are good bits of advice.

That said, I own a Steam Deck (Oled model), and it's surprisingly competent with BG3. Only place it stuttered was Act 3 and one of the patches addressed that. It also runs emulators very nicely, and despite it having Linux as its operating system which you may or may not be familiar with, there's a lot of easy tools out there to hit the ground running quick.

[url]https://retrodeck.net/[/url] I'm partial to this myself. 

I can vouch for it being pretty comfy to do what you're wanting to do --- but there are for sure cheaper options if price point is the big sticking factor. Especially since you'll want/need some accessories to get a "full computer" experience you may be accustomed to. And again, if you're unfamiliar with Linux, there is a learning curve. 

Hope you find what you're looking for.