Correct me if I'm wrong, but the tool in the OP sounds like a crowdsourcing effort to collect the data the Facebook tool can tell you across multiple users and multiple sites.
That's not really the same thing as a tool that tells a single person that the site they're on uses meta pixel as it happens.
Correct. The Facebook Pixel Helper is used to test that the pixel has been installed correctly and events, both standard and custom, are firing correctly.
That's not really the same thing as a tool that tells a single person that the site they're on uses meta pixel as it happens.