Look at the players he is training with (i.e. playing with multiple times a week) - Foden, Kovacic, KDB (when back from injury), Grealish, Nunes, Doku, Alvarez, Haaland. Surely he can learn something from that lot to apply to his own game.
He should do what Palmer just did.
Stay and learn from Pep, try to get a regular position and if not by next year go to a club permenantly. Don't go now and take the risk of being with a lesser manager and lesser players. It'll probabl;y be fine ...but just fine. Instead of potentially great.