Asks HN: Solo founders-How to respond when customers ask how big is your company

I've built an MVP and am talking to a prospective customer. They would be my first customer. They're asking how many people are in the company and I don't know how to respond to that in a reassuring way. It's just me.

Some background is I've built a pretty niche / domain specific product, so there's actually no one else doing what I'm doing. The MVP works. I don't have any customers yet (some trialing).