Ask HN: How did you overcome your speech stutter?

Hoping to hear from data-driven folks here who have managed to successfully overcome speech disfluency/stutter in their lives. I have a four year old whose blocking/disfluency/stutter is getting worse by the day. He already has virtual speech therapy sessions 2x a week. I'm really worried about what will become of him in the American high school system with its rampant bullying, and then about the pain and suffering the world will inflict on him. What can I do to help him overcome this?