I have a lisp, a stutter, and would be happy to live in a cabin in the woods far far away from civilization... but I got out of tech and now make a living in real estate and I'm active in politics. If I can learn the techniques to play an extrovert on TV, then anyone can do it. You have to have a plan for how to develop the skills and you have to put work into it, but it really is possible for anyone.
I will email you, but really I don’t know that I can be much help. I did speech lessons as a really little kid, but don’t think they helped much with the lisp. The stutter comes and goes - I will suddenly have a run where it’s happening a lot and then it goes away. Not sure if it is tied to stress or sleep or ?? Started very young but has never been so pronounced that I’ve sought to do anything about it - I generally don’t even think about it, but lately it’s been back again.