[joshstrange]

I think the logistics of this are too onerous for a site like HN. Even Reddit doesn't have anything like this. Between search engines/crawlers getting a different page than normal visitors, X free articles a month, and per-articles paywalls (such as sites that have removed the paywall for all COVID-19-related content) I think there is no easy way to tell if a site has paywall or not.

You could probably create a list of sites that have a paywall anywhere but I'm not sure if that would really provide a huge benefit.

For me, if a site has a paywall and I'm not willing to pay for it then I'll often read the comments to determine if I want to consider paying for it (normally only after I run into the same wall multiple times) or if I want to go looking on the internet for other reporting on the topic.