I don't have eyes on the roster, so I couldn't say, you have to talk to the U21 manager for that. But he's clearly a player aimed at NT rather than U21, so I wouldn't focus on the U21 as objective.
You will also have to decide what kind of profile you want for him in the end. If you're aiming towards SF rather than PF, outside training will last a little longer, thus the 1v1 training as well.