I'm not really informed on the youth teams these days, there are posters with much better knowledge, like
@khoazany @AltiUn @top1whoisman
They can answer on the U21 captain.
On the Arsenal kid, i would be very surprised if he plays any meaningful mins, maybe a debut and few mins just to get a feel of professional football. He looks physically strong, something that should never be underestimated. I expect few mins as a sub during last few mins of the game.
We have Hojlund, Zirkzee, Rashford, Amad, Garnacho, Mount, Bruno, Antony, Sancho who all plays in attacking positions, some of them are wingers but players like Rashford, Bruno, Sancho will be played as CF to make room for others. With such bloated squad, it's difficult to give mins even in cup games.