You can turn into a futanari for certain scenes but she returns to her base form (dickless female 😔) afterward. As far as not sleeping with men, that’s not intended, but may sort of be possible, but more as a challenge run than anything. The game is really focused on the female-on-male succubus fantasy though, so it’s definitely not the intended way to play. If you like SS but want to just fuck girls all the time, Hex has a “yuri mode” that basically makes lesbian-only playthroughs pretty easy but that game doesn’t have futa content yet.
can confirm this is possible, this is a simple tl;dr
get useful potions (will be using one to get marker license)
grind prostitution for 4 trait points
masturbate for self love perk, "Expose yourself" for noSham
get Self Sufficiency, Self Actualization, Self Satisfaction, Selfish: Stored Pleasure
using stored pleasure masturbate as futa 3 times
buy cauldron
craft own brand
get license
sell panties
in chapter 1 you get access to maid academy, sending witches can grant you semen & male urine, making the rest of the run trivial
just make a backup frequently so you dont pick the wrong option accidentally
spend way too much time searching through the source code to find this
afaik you need to be futa at least 3 times for the alchemy quest
you could get rare ingridients instead, but then you need something for a license