Thank you for the replies. A part of me is actually quite intrigued about co-op but it is totally alien to me in a CRPG and I always loved losing myself solo in the worlds of BG and similar games. I had a blast playing Vermintide 2 and Diablo 2 co-op back in the day but these are not story driven RPGs.
I might be persuaded to try co-op eventually but I think there would have to be some considerable changes to draw me back to try the game once again.
I still suspect it is a strong majority that will play BG3 solo but without the data my opinion is sort of moot.