I think he'd look good in La liga, would suit him much better. He doesn't have the physicality or pace to be a PL winger. Could be a player to keep an eye on should United not improve this season.
You could put Mbappe in this United team and he'd look like Oxlade-Chamberlain. Sancho is more talented than Foden, but you won't see it in this team unless something changes quite radically.