The Ready State Virtual Mobility Coach is like having a virtual Kelly Starrett in your pocket.
Glad to see the site has been helpful! Keep working on working to improve the pistol archetype and working upstream and downstream of the issues. However the issues you are running into may be because you still collapse your arch with movements involving DF. Check out the 27 squat video to work in a motor control drill and use it to focus solely on how far you can squat without your foot collapsing to the floor.