Back in 1E they did do a paper copy of Pool of Radiance, and I seem to remember something similar for PoR 2:Myth Drannor for 2E.
Personally, I'd do a "parallel" story - something that runs in the same area and has similar story beats but complements the video game without duplicating it. Have a couple points where it intersects with the video game on major story points (I haven't played the full game, so I can't comment directly on which encounters/areas I'd pull in, but the Druid/Refugee Fortress from Act I seems a good point).
As for the NPCs, probably have them in the back if you want to include the ones from the game to meet as well as a couple new ones if the DM/Players want some unique characters to add - each with an interesting background to play off.
I do like a lot of the custom gear from BG3, and I'd try to pull in as much of that as I could.
What I would really like to do is include an "oracle" system in the back so you could play it solo - or use the system for other adventures.