Re: ankle mobility help needed
From your videos, you seem to be lacking a little ROM in ankle dorsiflexion, but it is not something that should hold you back from squatting. I don't have much better dorsiflexion and I can squat and keep my heels down just fine. I think your issues could be resolved with just some good coaching and cueing.
Have you tried cuing yourself to 1) lift up your big toe and 2) sit back into the squat while shoving your knees out?
The 2x4 drill mentioned above or squatting while facing a wall may also be very useful drills.