I like your statement "If" they beat Milan, then Hakimi would be very much qualified to be the next African footballer of the year, cause of his good contribution to his team Paris Saint-Germain in both the Champions League and French Ligue 1 moreover he's already won the Ligue 1 so winning the Champions league would make him the best candidate for the award.
Failure for his team to win the Champions league, then Mo Salah would be the favourites candidate followed by Hakimi or Osimhen, I believe they might even consider him as runner up before Osimhen due to how relevant his league is compared to the Turkish League, Osimhen has been spectacular this year if only he was playing a bigger team in one of the top leagues.
If PSG fails to win the Champions League it will reduce Hakimi's chances of winning the award. A loss will put the Morrocan player in the same class as Victor Osimhen and Mohammed Salah, who both won League titles. Salah might have a slight edge considering that the English Premier League is highly rated than the Turkish and French League. But in my own view, Hakimi still stands a better chance of clinching the African Footballer of the Year since his club made it to the UCL finals.
I also feel that Hakimi will win the CAF men player of the year awards whether PSG wins the Champions League or not, my reason is because there is politics in football now and for the fact that Hakimi has made visible impact to PSG and won the France Ligue 1 title and also made it to the Champions League finals, it will be a good rating for him unlike Victor Osimhen and Mo Salah that only won league titles and neither Galatasaray nor Liverpool made it to the finals in the European Competitions of the Europa League and the Champions League. I even doubt if Victor Osimhen will be given the award despite his immense contribution to the Super Eagles and his club Galatasaray and for Mo Salah, he also made great contributions to Liverpool in the Premier League but it's not fair enough to crown the award to him. Hakimi indeed will be CAF favorite to win the African Footballer of the year.