the game is basically te real world so te closest to futa would be trans females
If you google it, you'll also see that intersex folk have a tiny, tiny chance of both genitals being active like they show in various hentai. The dev team want to be respectful to intersex folk, so they won't be patterning it off of fetishes if it gets in the game at all. The previous poster is right in that trans females are as close as you're gonna get