Mystique has a futa version!
For all the details on the character: https://hub.virtamate.com/resources/mystique-woman-snake-both-very.38816/
This look is a collaboration, with the conversion done masterfully by @Shioro, especially considering how much work it takes to clean up seams for a scaly skin!
Check out more of his work at https://hub.virtamate.com/members/shioro.4509/#resources and https://www.patreon.com/Shioro.Character Smoother/Tessellation plugin recommended (removes the square boob geometry).
Seen here with alternate Mystique Body morphs (from the Mystique Female set, which is also available to "Angel"-tier Patreon subs):
