For now, the futa content is generally designed without balls, though details may vary by character or scene.
Viewing post in BattleMaidens: Break Duel comments
It's not currently planned, but I won't rule it out completely.
At the moment, the futa content is designed around the characters themselves, so replacing it with strap-on content would require more than just a simple toggle. Still, I'll keep the idea in mind as a possible option for future content.