I think the right decision would be letting Rasmus Hojlund go and meet his master at Bayern Leverkusen since ETH is also considering coming for him, Napoli is also interested.
Serie A will be the best option for him, moving to the league he was once comfortable at before his move to Man United and at Napoli he has a better chance of medal and improvement under the management of Antonio Conte than under his former coach at United who signed him but couldn't bring the best out of his signing. While Bundesliga is not really tasking in compare to the EPL moving back to Serie A is better for him.
One of the main reason why Hojlund failed to adapt with Manchester United because Premier league has different game of style compared to Serie A and mostly the clubs from this league playing with very aggressive this make Hojlund having trouble to develop his skill and scores goals and with moved to Serie A i think Hojlund have a chance to restore his confident especially Hojlund is the former of Atalanta player and i think he knew to adapt with this league
Hojlund should be thinking realistic that when Ruben Amorim still the coach of Manchester United he has no place anymore in this team so i think Napoli could being an good destination for him and the recent news about this transfer is both representatives still under negotiation but Manchester United has accept the term which given by Napoli so in the near future i am sure transfer will be finish and Hojlund is the new player of Napoli