I guess this rabbit hole continues if one asks what the point of such testing could be. One thing I'd find useful is that I could take screenshots (or live demo this site) if I was doing some non-web-development thing such as doing a presentation and wanted to explain WebAuthn flow or something.
Because if I was a developer doing development, I'd test browsers with what I developed.
Or maybe you are a developer of that is using one of the features for the first time. Now you can check out the permission flow without having written any code. Similar to live examples in MDN.
