Napoli is different, they can lose Osimhen anytime in rest days of summer transfer season and Lukaku is a perfect replacement for Osimhen. The striker already worked and had good time with Conte in Inter Milan years ago. Chelsea know that they can not sell a striker who is more than 30 years old with very expensive transfer cost so accept the deal from Napoli will be better. A longer they let Lukaku moving to other clubs in loan transfers, a bigger financial loss they will get.
Chelsea must be able to make a wise decision about this before they suffer more losses on the financial side, because when there is a team that is looking for one of the players who is no longer young, of course there must be a better attitude from Chelsea so that they can also get a little benefit from it. And for Napoli it must be the same if they don't want to keep Osimhen for a long time, especially if Osimhen himself has the desire to move to the Premier League in the hope of having a good career there.
While there are people interested in Lukaku, I think they can sell him for a high transfer fee. As the player ages, his value decreases and he can be transferred for a lower fee. Transfer efforts between Napoli and Chelsea should accelerate. If this continues, both teams will suffer losses as the transfer window ends.