I can't help but feel like that's mostly all I have to bet on, though.

There are other things that can provide the same benefits. Off the top of my head: a job where you don't work from home, other coding boot camps, or CFAR. If App Academy falls through, you can pursue something else.

Something that makes this even more frustrating is that, had I realized enough of this just a year or two sooner, my opportunities to do something about it would have been far more numerous, simply by virtue of being at college

I don't know anyone who doesn't feel the same way about college, although the specific regrets vary from person to person. It is incredibly frustrating.

"Gain the ability to do things outside the house" is more or less one of my current goals, not that I know how to achieve it.

What's the biggest difficulty standing in your way? Is it the physical travel or the social anxiety or something else entirely? If it's a matter of location and transport, the first step is almost certainly "acquire money." (Given your situation, I think "acquire money" is a hard but solvable problem. Maybe do something like earning two dollars on Mechanical Turk to break down ugh fields and start a success spiral?) Step two would be either "turn money into transportation" or "use money to move to civilization."

More importantly, you can start building your skills without leaving the house. For example, if you're training basic social skills, you could call an acquaintance from college or spend five minutes on chatroulette. Or work on getting to the point where you can move through your own house without fear—it sounds like that would improve your mood and productivity dramatically, and the resilience you'd acquire will help you everywhere you go.