How does this product make money?

It doesn't. Making money isn't the point of this product.

Do you use Google Analytics?

Nope. We use Plausible Analytics. They are a privacy first alternative to the big analytics players like Google.

Why are you open source?

To promote trust; so that people can see we do what we say we do.

How do I know the linked repo is really what is deployed?

I actually don't know how to prove that. It is a problem for any OSS I imagine. However I promise you it is.

How can I stop someone taking a screen shot?

In short, you can't. Taking screenshots is a function of the operating system and can't be blocked or overridden by a website.

Further to that, even if it was possible there is no way to stop someone simply taking a photograph of the screen. Or, even more simply writing out your note on paper. To that end Burner Note and similar products make no effort to stop screenshots or copy / pasting. If the person you're sending a note to wants to keep it bad enough then they will. One way or another.