After casually recalling a couple of fanfics I discovered that there was a believable way to involve Adrien in the season finale without compromising his identity in front of Monarch or Ladybug.
Okay, so in my version of the story Felix infiltrates Adrien and Kagami's cage and tries to rescue them, but Adrien doesn't know if he can face his father under these conditions, so Felix and Kagami convince him that he has to take more initiative in his life or he'll never get his freedom. Finally Adrien comes up with an idea.
With the help of the sentimonster camera, Adrien projects a video around the world where he reveals that he doesn't want to be a model and that he only does it to please his father. The message will set many of the akumatized free.
Monarch realizes that he is losing akumatized and Adrien's message reaches him in his alliance. Instead of Emilio's message, it is Adrien's message that tells him that he just wanted his family to be happy again and that although things are not perfect, he would like his father to accept him as he is.
Gabriel goes into a mental breakdown, knowing that the repercussions to the company for his son's confession will be very serious and he is no longer sure of fulfilling his wish.
Y... Instead of making the wish Gabriel falls agonizing in his last moments of life and talks to Marinette about the great mistakes he made in vain, he begs her to please make the wish to revive Nathalie by using himself as a sacrifice and although Marinette does not want to do it, in tears she resigns herself and makes the wish.
Either that or they both pay the consequences of their actions and Amelie moves permanently to Agreste Manor and dissolves the company.
So it not only gives Adrien and Felix something to do, not only does it humanize Gabriel, but it also prevents the world from ending.