I don't think being able to reverse engineer your project is actually a good qualification for hiring you, considering your employees don't need to do that.
Also, isn't she a high schooler/freshman? There's always internships but it's best to do other things before grinding those out.
If someone understands your codebase without your sources and docs - you can bet that they will also understand it with the help of those. Usually better, if the docs have any value.
And this is kind of a valuable skill, considering how many coders don't understand their codebase even with docs.
It’s certainly true that such people are very capable, and would be good people to hire for many kinds of work. However corporate environments don’t typically like people who are willing to work around artificial restrictions. This particular skill set (which is what reverse engineering is) may even be (perceived as) a negative at a company like Apple.
Much of it (LLVM) is open source, and for the rest I don't think understanding the inputs and outputs is actually that closely related to being able to maintain the bits in the middle, or come up with new bits.
Most employees would probably be well served being able to reverse engineer things. Sure, you might have docs on how your graphics pipeline works, but then you’re probably going to be looking at commercial software that runs on it.
Actually I think it’s more being unsure of what else to do in life and for want of a structure, and money is one of those things people are unsure of. However looking at her work to date, she can find money on her own terms. She seems to work well on her own terms in her own structure. The thing that could hurt her more than anything is working under someone else’s structure and terms.
Too many people involved in technical hiring, and too many pointless interviews. It's likely anywhere they went to interview, the people there would have no idea how good they were in the first place.
If I were in their position then maybe applying to random jobs wouldn’t be the right strategy. Instead either ensure you have enough contact information available for leads to come in, or reach out to connections at companies to get warm introductions. It won’t work everywhere but it needn’t work everywhere.