I didn't get anything that resembled Dembele in that video.
He actually plays like the Pogba who tore apart Serie A - alot stronger and bigger than a lot of the opponents he's up against, demands the ball and has bucket loads of confidence when he's on the ball with. I actually think a Dembele/Onomah partnership would work because both are hard to get the ball off in possession, both do a defensive shift and pass completion for both must be high 80s.
Not the best video (no where near as good as the YouTube vid posted of Onomah) but this was when France won the U20 World Cup and Pogba was star midfielder - pretty much the same age as Onomah, you can see the similarities in their game (beyond Pogba shooting in nearly all of the highlights), strong on the ball, bigger then most of the opponents, neat foot work etc.
Based on the video you posted I'd say other than both are midfielders, won the tournament and had an advantageous physicality, they had very little in common.
Pogba comes off as a selfish, arrogant cunt, with terrible decision making and a desire to show off, whereas Onomah seems happy to be the engine of the team. Pogba seems to want glory for himself, Onomah seems to want to his best for the team.