Sancho can perform without much space due to his fantastic first touch and technique to go along with his superb decision making, passing and dribbling. He's a completely different level of player to Daniel James and can contribute without space for the reasons mentioned above.
You play Pogba in a double pivot and Fernandes slightly more advanced. Fernandes is also a player that is tactically very flexible and has high work rate, so he can adjust to different scenarios in a game. For example, Fernandes can drop deeper if Pogba is caught too high up the pitch to maintain balance.
Ole has gone on record and stated he expects more from his fullbacks going forward and said they must improve in that regard. And IMO the reason for him saying that is due to fullbacks being a very important weapon in today's game.