Actually PSG performed quite well in the UCL. They made it to the semifinals and that means they are among the elite European clubs. But the problem is that Ligue 1 is often referred to as a farmers' league so not many media highlight Ligue 1. Honestly in my area if there are several matches in one night people will choose to watch the EPL, La Liga or Serie A rather than the Bundesliga or Ligue 1. If Osimhen wants to be a UCL star I think PSG is still very viable because they will almost always play in the UCL every season. But your performance in the league will not be highlighted by many media and this will affect Osimhen's career.
This is also quite reasonable for Osimhen to consider because it is very clear that Ligue1 is still less popular than the EPL, La Liga and Serie A. So Osimhen himself must be willing to accept that this happens to him if he really wants to be in Ligue1 next season in the PSG squad which is generally always in the UCL, but is not very visible through the media when playing in Ligue1. Even though he himself can also make his career so brilliant in Ligue1 that in the end he can also make the choice to go to another league like Mbappe is currently doing.