I've seen a lot of companies list logos if just a single engineer or team is using the product.

Everyone does that. Some random startup "We're used by Google!". More often than not some random engineer signed up for a trial or some tiny department somewhere is using it for some internal thing

I was under the impression that "individual engineers ..." is basically implied always, if not just outright lies, I don't trust these listings very highly. Except when its clear that the companies are actually customers. Like; how do I even add my company to this list? Email them?