Throwing my hat in on this one too, I've got TTRPG products I'll have to manually handle for this sort of thing, and it would be really great for it to be handled directly by the platform.
On DriveThruRPG, you can simply select another account and assign them a percentage of the revenue of the product, which is how I handle this on there. One account has to be the "publisher" who gets the management rights on the sales item, but you can at least send someone their proper cut. As for direct deposit versus collection by itch, I don't see why there'd be a complication here. I'm new to itch, but it looks like they already have a page for assigning your percentage split to itch, I can easily imagine a similar page per-product for assigning revenue splits with other users.