Hey! This can be added pretty easily if you're willing to download the game and edit the Chrome HTML Document code :)
In my one because I play with a male only campus I set the AMAB gender to have both a penis and vagina so I'm going to explain what I did but you can use it on any gender I believe.
Right click on the HTML Document Code, select edit with notepad (or equivalent), select Edit in the toolbar and then Find, paste this into the search bar (remove the quote marks)
"setup.species.human.genders["nonbinary amab"] = {"
Then on the bit that says parts at the end where it says ""penis", "balls"" change it to ""penis", "balls", "vagina", "clitoris"" and if you've done it correctly you should automatically have both a penis and vagina when you choose to start as a AMAB character :)