Google famously passed on the guy who invented Homebrew, so at least you're in good company. As others have said, the interview process selects for (wait for it) ... people who are good at the interview process. It's kind of like the SAT and college. If you want to get in, you get good at the SAT, regardless of its relevance.

Instead, maybe seek out the companies that go bonkers for your OS project and can't wait to turn you loose inside their company. They're out there and I suspect it would be more enjoyable to work for them. Good luck and don't despair!