Well, the judges have to do their job properly. I have not come across one person in real life or online that has stated they believe Wilder won the first fight against Fury (which officially ended in a draw because very dubious scorecard judging) therefore everybody who is wondering how Fury won the fight, has a right to question it. I just cannot get over the 96/93 scorecard, there is no legitimate way I can think of that any judge could have scored the fight 96/93 in favour of Fury.
As for Ngannou, now is the chance for him to make more money and even try for a title fight because he is not getting younger. He is in great physical condition at the age of 37 but he needs to maximise his opportunity before the world simply forgets about him or time catches up with him.
Judges are present to score the fight, and their decision is final. Even if some argue that Ngannou was robbed, the outcome cannot be changed; Fury won the fight, and that stands. If Ngannou's camp wishes to pursue a rematch, they can request it, but securing one won't be easy, especially since Fury has a scheduled fight ahead—likely the most significant one of his career.
Ngannou may consider challenging other heavyweights to gain more experience in boxing and secure wins. This could help him become more comfortable in the ring and better prepared for a potential rematch with Fury, who is expected to train rigorously given their previous encounter.