Are there any notable individuals who began life nonverbal but learned how to communicate orally and became successful?

I have heard many times that Albert Einstein didn't speak in his early years, so went to fact check it. Turns out it is not true, but I learned a fun fact that is hard to not share:

When he was two years old, his parents made him excited that he would get a little sister to play with. When she was born and he got to meet her, he was slightly confused and asked about the baby: "Where are its wheels?"

Temple grandin

I believe Oliver Sacks was non verbal as a child until 5 or 6 and hated music until his teens, where he took an interest in medicine and became a remarkable neuroscientist.

Helen Keller

Me. I talked using sing language in my early years.

That might be a hard list to create. While I understand the spirit of the message, I think it would be difficult to objectively define "non-verbal", then create a list of people that meet that criteria since they would have to publicly self-disclosed. I imagine we would mostly see this with autistic people that are advocates for the autistic community.

Are there any notable individuals who began life nonverbal ...

Literally everyone.

I think you mean something more like "... still nonverbal at the age of 5+ ... "

To that, I don't know of any. But I'd bet there are at least a few. The world is a big place, and betting against the existence of an extreme outlier is usually a bad bet.