A lot's changed since 2024. The decentralization primitives were always in place, but now they're being actively used. Hosting your own PDS is quite viable if you're tech-inclined, or check out Blacksky.

There's also rumors that the W European social network launched a few days ago is built on ATProto.

That's rather outdated at this point; in particular see https://en.wikipedia.org/wiki/Blacksky . Far from perfect, but it's not as bad as it was.

That Wikipedia article doesn't talk about anything relevant as far as I can see. Can Blacksky users DM Bluesky users? Can they search all of Bluesky's posts? Are there any issues with reply visibility?