It's true that the change of coach was what resulted to the poor performance of Napoli last season and that is why the club have brought in Conte to see how he can bring those victorious days back to the club. I feel for Osimhen that he is ready to leave Napoli but no club have shown good interest on him who knows maybe he will be lucky to have a new deal before transfer window closes.
I believe that if Osimhen is sold Lukaku will be brought to Napoli because this has being Conte plns since he took over as the manager of the club. The reason why Lukaku is not yet signed is because Osimhen is still in the club any positive news from any club that needs him.
Osimhen doesn't have many options to leave Napoli, and the main reason is his high transfer fee. For now, a more realistic possibility for him is a move to Chelsea followed by an exchange for Lukaku, at least this is the only thing that is currently being discussed about Osimhen that I have seen. Spalletti may not be the best coach, but it was with him that Napoli achieved the championship and reached the peak of their form.
Victor Osimhen had the opportunity to leave Napoli last summer that many clubs were very interested in him after his incredible performance of 2022/23 season that he finished as the top scorer in the Italian Serie A but decided to stay back and now that the club doesn't want to keep him again, getting a club that'll meet the financial requirements of signing him have become a big problem. It was initially reported that Paris Saint Germaine are interested in him but that report seems to be a mere rumour because we're yet to see any official statement from the French champions that suggests that they're genuinely interested in Victor Osimhen. Napoli is reported to be interested in Romelu Lukaku while Chelsea on the other hand is interested in signing a quality striker which is why I think the two clubs can just go for a swap deal that'll see both strikers move to opposite directions