I don't understand why Osimhen shouldnt stay at Galatasaray. Manchester United and Juventus do not have the Option to play in the Champions League while Galatasaray will be playing there.
The fans Love him, he loves the fans as well. That might just be a big Project for the Galatasaray board but they have finally put a vision infront, so if osimhen wants to stay, the economical part wont be the biggest issue. It's all about Osimhen, and the reason why the Osimhen deals are not advancing is that galatasaray is in the middle of the league title race, and after finishing the league, Osimhen will be ready to look at all the contracts he got. Simple as that!
Osimhen is currently leading the scoring race in the Turkish League, it is clear that he will attract the attention of more top teams. There is no point in him moving to Manchester United, because they are not even sure that they will get a place in the Champions League, and their position in the English Premier League is also very bad. So I don’t see the point in wanting to move to such a team. Everything is better with Juventus, they are still in the top 4, and they still have a chance to get a place in the top 4, so I would consider a move to Juventus if I were him. Yes, Galatasaray will also get a place in the Champions League, but most likely I think that they will not get out of the group stage, because their class is not that high at the European level.