I'm a solo founder. Honestly, I was a little concerned with the question specifically outlining this fact, even though it assured us not to worry.

I'd prefer not to be a solo founder, I just haven't found anybody suitable yet. I'm hoping that changes in the future.

Probably the most notable answer to your second question of successful single founder applications is Drew Houston with Dropbox.

Didn't he get rejected and have to re-apply with Arash?

The first time he applied it was with an test prep idea, if I recall PG correctly, and he was rejected.

The second time he applied with Dropbox, he was accepted. After being accepted, he got Arash to join him.

It seems to me that about every batch there is a single founder. But they tend to find co-founders after acceptance.