Don't bother getting a formal education if you don't need it. If you're already working as a product manager at 19 remotely then you're better off than most people in this group.
I've been working in tech for about 14 years remotely in Latin America and Asia. Don't worry about longterm visas right away until you're 100% sure. You can easily find a couple spots you like in SE Asia and rotate between them easily.
Make sure you apply for the Vietnam visa well in advance. I applied 10 days before and last week it was only approved 20 minutes after my flight from bangkok left without me.