I still feels that Victor Osimhen's interest is in the English Premier League ,and would do everything within his powers to stay fit, so the need to joining Galatasaray became necessary, if Osimhen wanted to join the Saudi professional league, this a decision he would have been a decision he would had made earlier.
Ofcourse the English premier League where he can get an opportunity to be at the champions League is a dream for him which I believe he would want to do almost every thing to make it come through at this time. If he eventually fails to get to this point in his career, somehow I believe he may not feel fulfilled enough so he would want to make sure he gets to that point by almost every means possible within his strength because it's needed for the career history he will be building. Joining Galatasaray wasn't a bad one at all, for me he's still got chance from there but away from there he would have lesser or even little chances to go back into the English premier League in the nearest future.
It depends on the club that recruits him if Chelsea recruits him then the opportunity to play in the Champions League is very small because this club is no longer the Chelsea that we used to know but if the one who recruits Victor Oshimen is a club like Arsenal, Liverpool or Manchester City then he will have the opportunity to play in the Champions League to realize his dreams, but it seems that these clubs are not very interested in the near future but if Victor Oshimen is able to provide stunning skills in the Europa League with Galatasaray maybe the top clubs will compete to get his signature, I believe Oshimen can return to his best version because he is a talented player.