just some theorycrafting -
i think if larian introduced a mini prelude to the actual event or scenario that has you scooped up by the mindflayers then that could be a good opportunity to introduce some tutorial like mechanics, like dialogue rolls, movement, camera control, and trading, and also answer some questions regarding what your character was doing before they got thrown in the mindflayer pod - i envision that as a player you create your pc (not your dreamer quite yet tho), after which there is some minor narrative dialogue/power point like slides related bringing the player up to speed on the world of FR/BG (like the recent avernus debacle and what the dukes have been doing in response, etc) and using your selected character background to make the prelude more personal along the lines of youre a soldier returning to baldurs gate, or you are a sage traveling from candlekeep to the gate, etc. (obviously more 'out there' character concepts would need to be more finely tuned) but in such a mini prelude you would then get a really limited snapshot/tutorial of BG (or yartar or wherever you get picked up) that would give you a chance to also purchase your starting equipment.
im envisioning you dialogue your way through BG front entrance flaming fist, have some opportunities for some minor dialogue with some BG refugees to give some added FR atmosphere, you get to talk to merchants/quartermasters at the front gate area where you can select/modify your starting gear, and once that merchant dialogue ends the mindflayers attack and you go from there and create your dreamer once the trailer gets back to the tadpole administration moment - i think it would be an easier phase in that jumping right into battling imps and mindflayers in the seven hells
(also tangential, but i would think that a lvl 1 character would have a much harder time battling imps in hell on a planar spaceship - unless the devils are in on it? but that theorycrafting gets into larians plot that we dont know the full details of as of yet)
I really like that idea a lot!
I hope they consider it.
The way the opening cinematic is set up I think there are two ways to do it depending on when (in time) you want to interpret the tadpole in the eye occuring... Either PC was scooped in Baldurs Gate and slug scene is happening while the attack is still going down, or slug scene happens earlier chronologically than scenes are presented and Charname already on Nautilus when it arrives. In that interpretation Charname could have been scooped up from anywhere. I think the easiest would be to give a tutorial zone that tweaks to Charnames race/class/background in a way that makes sense for a set up. I think pretty much every character could find a reason to be in Baldurs Gate, or Avernus, or the Astral plane wherever the Gith are bombing in from. The slug scene could be at any point then, since the viewer can provide the chronology/continuity and it happens before char creation anyway.
A Baldur's Gate prelude would be a nice way to insert background, and to showcase more of the UI and basic menus in a tutorial zone where the pacing wasn't quite so high drama. You know like a generic Inn rather than a crashing Nautiloid hehe. Prelude Tutorial could come before the Prolgoue and play into the set up there, but be a separate launch.