I half did this: after sophomore year, I left high school for what's now called Bard College at Simon's Rock, a college specifically for younger kids. tl;dr if you think you might be ready for college you should look at it. There are scholarships.
I have no regrets about that. It's as demanding as you want. About 2/3 of kids there get an associates' to transfer to another school after two years; those that stay all four do a B.A. thesis. Some folks who transferred reported being bored at their new schools, but I don't have much of a sample. :) I'd probably have had a slightly shinier-looking résumé if I'd gone on through high school, but there's more to life than that. For me the résumé thing is moot (the Rock actually helped; I got work through a teacher referring me to an alum), and plenty of classmates have done well in tech or law, become doctors, gone into research (including in hard sciences), etc. It produces a good number of high achievers for its small size and high acceptance rate, probably because kids interested in rushing into college are a sort of funny pool already. Occasionally bureaucracy requires some grad to take a GED exam because they left high school, but that's straightforward.
For high-school me, the focus on the liberal arts and the beliefs of folks there really contrasted with how I looked at the world at the time. Same would be true for a lot of folks here I figure. The tension from being exposed to something different was productive for me. Sounds icky I bet, but what you need to learn is not always the stuff you come in wanting to learn.
Anyhow, the site is https://simons-rock.edu/. Hope this is useful to folks.