Osimhen after last season is probably rated as one of or even the most valuable player in the league and one of the top top strikers in the world. he's on 4.25 net, will be looking to at least double that and Napoli probably top out around 5m or 6m max, clearly his days there are numbered.
imo the summer to sell him was this one, next summer he'll only have a year remaining on his contract and that usually puts pressure on the seller.