No. The have nag screens for donations, but they don’t block on principle.

no, I’m very certain I’ve never seen one, this article certainly doesn’t have one

Guardian have a paywall for their mobile app, you get a quota of articles per week.

However the website which is almost identical is unlimited

For me, the page doesn’t allow me to scroll past the first sentence of the article.

Maybe it’s because I’m using mobile Firefox with uBO? I only managed to read the article through here.

Not a paywall you have to pay with money per se, but they require you to have an account and be logged in to fully see a profile, a post and its comments. Same goes for Facebook.