I'm pretty sure Madodev stated that Futa content isn't being considered a while back. Even if it were, I'm not sure how it would be implemented, grappler enemies? Maybe have some humans, slimes, and ratkin spawn as futa to grapple your party members, but that may ruin the flow. Cursed class? The only cases I can see are to grapple enemies, (kinda pointless,) or granting some kind of powerful support abilities that grow desires and crests as a trade off which doesn't sound like it can be balanced, ala spawners in Clash Royale.
Something can be done with the enemies, like having a futa variant with different grapple animations, i remind you that this is a porn game 🤔
The "that might run the flow" part sounds like you just don't like that type of content, in which case there's already an option in the menu to block/hide content you don't like.