your ability to writing this out and provide in a liner way make it like a painting to me. You should have no problem in a real world work environment with the right support.

checking our your code, it's great as well, you surpass level of many engineers i know who has staff/principal in their title.

don't let the fact about those job or interview letting you down. You write out C code like nothing from these.

You're absolute a great programmer.

You will have better succeess doing your own SaaS instead.