“All platforms in the EU have to have a dedicated page on their websites where it says how many user numbers they have in the EU and where they are legally established,”

I think that's standard on mastodon and pleroma instances.

Under the DSA, platforms with more than 45 million users in the bloc qualify as “very large online platforms” and need to follow stricter content moderation rules under the commission’s supervision.

Clearly defined rules? How interesting... but moderation is a thing on the fediverse so, meh... maybe mastodon.social has to worry about it.

Smaller platforms are still required to comply with the law, but are regulated by the EU country where they have a legal presence. That’s so far unclear in the case of Bluesky, which was created expressly to avoid a centralized ownership structure.

And yet they're not decentralized yet... if ever. Anyway, servers are physical.

A while back i was looking for instances in the EU and while a few claimed to be from a few different countries, their servers were all in Helsinki...