Osimhen should have been sold in last season's transfer window for a fantastic price, because quite a lot of big clubs were interested in him. Now Osimhen's performance is starting to decline and yenru will affect his selling value too. Napoli's management may be speculating a little and Spalletti's departure is proof that management is starting to go wrong, affecting the performance of several key players. Before it's too late, it's a good idea for Napoli to immediately sell Osimhen and buy several new players from the proceeds. Yes, Chelsea and PSG might be the right teams for Osimhen.
The two teams you mentioned could indeed be very suitable options for Osimhen, but from my personal view it would be better if Osimhen were sold to PSG rather than Chelsea. Because in the English League it will not be easy for players like Osimhen to compete with other players. Meanwhile, at PSG, Osimhen can play more freely because the pressure in the French League is not that great if we compare it to the pressure in the English League. So the option to PSG seems to be a little better than Chelsea, although both teams are not bad for Osimhen.
I have different thoughts from you about which club Osimhen should join, because if he joins Paris Saint Germain I think it will be difficult for him to develop. Maybe being there will make him comfortable, because at least he can get the Ligue 1 title, but if we talk more than that then at Paris Saint Germain he will have less competition, and honestly I think that will have a bad impact on his career.
Meanwhile, if he moves to a club from the English League, then it will be a challenge for him, because there he has to prove his abilities as well as possible, because if not then he will be considered a failed transfer. So, in my opinion, this is a good thing for him, because he is required to be able to develop all the time to maintain and improve his performance so that he can be even better. This is a challenge in itself, and if he succeeds in doing it very well, then his name will be even bigger.