One of YC's most important lessons is to meet your customers in-person.
Back then, Billow didn't have a clear product direction and I had to solve this.
So I started flying to San Diego, New York, and Boston to meet potential customers.
I'd email them something like "I just happen to be in town this Thursday, want to grab coffee?"
Then I'd book a red-eye flight and show up at their office with a bag of donuts (like in this photo).
When you meet people on Zoom, they're overly polite. It's hard to know what they actually think.
But when you meet in-person, they are more likely to get out of their way to help you.