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.
If it's true as you say, that doesn't mean there is a possibility that PSG has already signed Osimhen because apart from Chelsea, it is likely that PSG is the only one who wants to spend a lot of money. For another club, Real Madrid may have that kind of funds but they have already got Mbappe, so it would be almost impossible for them to sign Osimhen.
Everything will be clear when the truth is revealed but somehow I feel that the club in question is PSG.
Real Madrid will not spend money to get Osimhen and I not even sure if Ancelotti has the desire to bring in Napoli mainstay player because currently Real Madrid has several great attacking players.
It is even reported that some players might only be on the bench when next season Mbappe is already playing with Real Madrid and if Real Madrid adds players it might be players in defender or midfielder positions because this summer several players in this position have left.
What is clear is that Napoli wants more than 100 million euros to release Osimhen and so far Chelsea cannot afford to spend that much money, even Arsenal have only been able to make an offer of 70 million euros for Osimhen.
No one knows for sure who will get Osimhen, whether it is PSG or Chelsea, what is clear is that if that amount of money is then only PSG can spend it, but on the other hand, Chelsea is offering two players Cesare Casadei and Romelu Lukaku along with certain amount of transfer money for Osimhen.
After all, being able to play in the Premier League itself is Osimhen wish and of course only Chelsea really seems serious enough about Osimhen transfer.