How to Improve Ankle Mobility for Deeper Squats Without Pain

I have always struggled with my squat depth and I am realized it is because my ankles are as stiff as a board. I am looking for how to improve ankle mobility for deeper squats without pain. Whenever I try to go lower my heels lift off the ground or I feel a pinch in the front of my ankle.

I have been doing weighted ankle stretches and using a foam roller on my calves but progress is very slow. I am wondering if I should invest in some lifting shoes with a raised heel to help in the meantime. I have heard that joint flossing with a voodoo band can also help break up some of the restriction in the joint capsule.

Does anyone have a routine that actually worked for them? I want to be able to hit a full depth squat with a flat back. I am also curious if I should be focusing more on the soft tissue or the actual joint mechanics. Any advice from fellow lifters who have overcome stiff ankles would be amazing!