I think Osimhen will prefer to choose PSG than Chelsea, if he has consideration of a good team management for him to develop. Luis Enrique is undoubtedly much better coach than Maresca, and Chelsea currently is not a good place to have development for talented players. Chance to play in Champions League is a factor for a player to choose a club, but I don't think it's a big factor anymore, we have seen many top talents choose a better financial offer rather than chance to play in Champions League.
Osimhen is still young, he is also a talented player and his goal scoring instinct is also very, very fast. When faced with two choices between PSG and Chelsea, of course he will choose PSG. There he was able to hone all his skills because he was handled by top coaches and had teammates who had above average abilities. The opportunity to play in the Champions League is also a very strong attraction, Osimhen will hone his skills even more if he often plays in big matches. Players his age must put aside financial offers to support his career with a club that wins the domestic league almost every year. He will also receive a salary increase or offer a bigger salary when he is able to become a key player in his team.
PSG has everything to be attractive for recruiting players and also the PSG team has strong enough finances so I think that will be a consideration for Osimhen to choose PSG and also PSG's progress or targets are quite good so it is likely that the players will continue to improve.
After Mbappe's departure, PSG had to look for a suitable replacement and in my opinion Osimhen is the right player to fill the void.