He doesn't have a tadpole so it's unlikely. Tadpoles seem to be the glue keeping companions together, and overriding personal motivation when playing as origin. He also joins party late, which make him barred from being an origin, and as far as I am aware, BG3 is still aimed to be a 4 COOP RPG.
Nonorigin companions would be great.
I did play a co-op game, and I don't see how nonorigin companions would cause issues with co-op. They would be like any of the origin companions who aren't picked to be played. I usually like to create my own character, anyways.
