Howdy!
Dominant gym content is planned, actually. It'll be at Hedon's gym when it's added. As for character customisation, FOXXX is firmly a "set protagonist" affair, and the upcoming main plot for the game centers heavily on that :3c
Apologies for the blunt response, but I believe it's warranted in this case.
Basil from Omori, the character you described as "Submissive and breedable", is depicted as between the ages of 12 and 16. They're a child or teenager, and I don't appreciate the comparison to the very much adult protagonist of my game.
I have banned you from posting here. Please introspect and conduct yourself better in the future.