Yeah, I like the backpack idea, maybe if it isn't too big there wouldn't be any clipping issues. But, I don't think they''ll do it, we''ll be lucky to get the doffing of shields to our backs and sheathed weapons. I don't think realism too high a priority in Larian's design.
I wanted to say I've yet to come across a game that does so, but despite Pathfinder: Wrath of the Righteous isn't nearly as good looking as Baldur's Gate 3, it actually does all these things here described. There are many more features in that game I'd love to see in Baldur's Gate 3. It's ironic how indie developers, despite their lack of budget, always have these grandiose ideas bigger companies don't bother to implement.