I agree that Leao might be a better option for Manchester United than Lookman. The two are good players but Leao proved himself in AC Milan many times and could adapt perfectly. I have some worries that Lookman will be the new Victor Osimhen, he needs to learn from his Nigerian teammate who was once, one of the best players in a season then he faded.
Lookman is the African Player of the Year and he has also won a trophy for it, but when it comes to the speed of adapting to a new team with a very different League, of course Leao is better than Lookman in that regard. But the conditions will still be very different when a player who is used to the Italian League moves to the English League which is quite competitive and the tension of the game is quite tight and quite fast. So maybe Manchester United are looking at other things than that so they start to look at Lookman more than a player like Leao even though Leao is also a very good player and also suitable to be recruited by a team like Manchester United.