Twitter could make itself real interesting if it took "community notes" web-wide. So many attempts at this have tried and failed, but Elon may just have the itch, audience, and disposable money to do it. Would also necessitate forking a special browser, since there would be no way to support web page comments in a first-class way in stock mobile browsers.
Idk, what Twitter has is much better than this since they are how people find content. Building some special infra and viewer for per-website notes just seems like a downgrade that gets worse and worse the more you try to hash out how exactly it should work.
Discoverability of comments/dissenting views is the key factor. I would bet that most readers of any given article on the Guardian site did not get there from Twitter, and therefore could benefit from a browser that displayed community notes. The details of knowing how to show what comments where are definitely challenging, but certainly worth another attempt with the capable AI techniques that could address previously intractable problems.
My recollection is that Gab made a plugin for browsers called Dissenter that did something like this, but they were banned from the Mozilla and Chrome stores under their moderation/censorship policies. I’ve never used it but I think it created a discussion on top of any URL. They ended up making a browser fork of Chrome but it probably went nowhere.