Sure, I'm just laying out some options, and plenty of shows have thrived having multiple plot threads going in different locations. Including Shadow and Bone.
Shadow and Bone keeps the focus on the actual characters though - I can't think of any scenes which don't include them, off the top of my head. The problem BG3 would face is that the only people separate from the main party without drastic changes which would lose what makes BG3 special and likely turn into into generic fantasy blather, would be Jaheria and Minsc, who I'm just really skeptical would make good viewing, given one of them is borderline mentally subnormal (terribly nice, sure, but he couldn't think his way out of a paper bag - he's a ginger cat given human form), and the other is a semi-irrational hothead. I guess you could like, have Minthara's story be a bit different and follow her a bit, but I think there's going to be a real "Why are we wasting time with these jerks, not with the cool kids?" deal, if they do the main party right.
That's the conflict as I see it - if you cast and write the main characters as they should be, as they are in the games, the interplay between them will be a big part of the charm (as it is in Shadow and Bone, or Willow for people who liked that - I did). You'll want to hear Astarion's latest put-down, or Karlach's wonder at something or terrible joke, or Gale's slightly-off and condescending explanation, which Shadowheart responds to with dripping venom. So if you take the focus off them, and start to construct the show as a more routine fantasy deal, especially if you spend long amounts of time with frankly dull and standard characters like the Duke, or random Harpers. Also the mystery is not hugely complex - it's got like what, three layers? And whilst obviously everyone who plays the game will know it, you still want to unveil it slowly for the home audience, so you can drop the real horror-bomb on them in Act 2 (probably late Act 2) discovering what's beneath the keep. The more you do stuff like focus on the baddies or follow "investigations", the more obvious it's going to be what's going on even to a new audience.
You can certainly split up the main party into smaller groups and individuals at times of course, that's to be expected, I just think it's following entire other characters for more than short scenes or cold opens that would be questionable.
Sorry I'm not trying to be overly down, especially not on you personally, it's just Netflix screw up a lot of stuff, and this is a really particularly easy thing to destroy the magic of and turn into generic fantasy that people wonder what the fuss was about. I hope that if Larian do sell it to Netflix they retain some kind of creative control/influence.
