I think YC would expect you to be a bit more earnest in your efforts to find a cofounder, e.g. move somewhere with higher concentration of talent and ambition.

I think YC would expect you to be a bit more earnest in your efforts to find a cofounder, e.g. move somewhere with higher concentration of talent and ambition. Solo founders are seen as risky to fund by YC, so what could you do to mitigate that risk? Finish something, and show traction.