I've recently been in a similar situation and it's very tough. Agree 100% on the LinkedIn (I didn't try AngelList) the quality was terrible, which I think is because of how easy they make it to apply, so you just end up getting randoms that don't actually have any interest in working for you.

I ended up finding peopl through a personal connection. After going through lots of personal connections that were not interested. I think that (unfortunately) one of the key things you are expected to bring as a founder is the connections to hire people.