Osimhen as said by their president in Dicember is already sold but we dont know to whom.
A reason on why we dont know yet is because it may go to EUA and there the market session will start in 1 week.
It may also ends at PSG, they needs to replace Mbappè somehow even if they are not spending so much money lately.
So TLDR, Napoli will have the money from Osimhen and they can spend for Lukaku.
I also thought as much because I am very sure that Napoli will not leave Osimhen in their squad for another season because the player has already lost interest in the team and if left there he will not add much impact to the team and he might end up being a liability that may end up leaving as a free agent despite all the money spent on him.
Last season’s transfer window should have been the best time to sell Osimhen because the hype was there that time and several teams wants him by all means especially Chelsea, but the management decided to keep him and now the hype is not there like before and teams will not be able to bring out big money to sign him anymore; therefore any amount of money Napoli end up seeing, they should just take it because teams has now know that they are desperate to let him go.