Re: ankle mobility help needed
I read over your other post as well. I can't do pistols (yet) due to ankle mobility yet I can squat fine.
Your heels twisting in is a symptom. The ankle most likely is tight but not the cause.
Most of the time I see this fault people have their stance too narrow and drive their knees forward instead of hips back.
Video would be good.
Squatting to a med ball can help teach hips back. Your heals go at the very front edge of the ball. Keeping torso in correct position you send your hips back and down until you touch the top of the ball without allowing you feet to shift. No bouncing off the ball. Use only enough weight to help stretch thing out but you can do lots of reps.
Use video or another person to watch your feet. The second the heels move stop and try again.