I'm really interested in your high school experience. Did you mostly work solo, or was there a lot of interaction with other kids? Informal tutoring, collaborating on hard problems, etc.
I will say similarly I think the 42 Code School in Fremont, CA mostly relies on e-courses and group collaboration with minimal teacher help. I have a friend who goes there. It is more college level. https://www.42.us.org/
I think a key thing with both of these schools is that to some degree the students wanted to be there. The alternative high school was opened in my area mostly to help people who really wanted to finish high school but were poor and dropping out to work, had a teen pregnancy, or were sick. There were a few advanced students who just wanted to finish early but that was a minority. A lot of them just really wanted to get a real diploma ASAP to get better jobs.