I dont think this transfer will happen at all. I think Man Utd went the other way and there are many rumours that they will get Cunha on that striker position. Osimhen will probobly go to some Italian club because i dont think he will stay anymore in Galatasaray. Defence is the main thing for Man Utd but i think they need to build on all positions
Napoli no longer want Osimhen since last season so I'm sure he will move in the next transfer window especially since his contract ends this year and Napoli don't have many options, let him go for under market value or for free. Cunha might be another alternative but it would be no problem if Manchester United brought in these two players they need some strikers as alternative especially if the rumors of Højlund's transfer are true, reportedly clubs from Italy interested in him.
If Osimhen goes to Manchester United, he will be really successful. However, we should not forget that Manchester United also needs change in the defense area. Because they conceded too many wrong goals and the defense is really having big problems. I think some players will leave Real Madrid and Manchester United can get the defenders. Or they may want to give a chance to young, promising defenders in Europe. Every Portuguese manager will want to create a Manchester United that will compete well next year.