Yes, that's an excellent post as well. I would add this one too: https://ianbetteridge.com/2023/06/21/meta-and-mastodon-whats-really-on-peoples-minds/
Fabriek
That's exactly the Meta we're talking about. The most likely explanation is that Facebook wants to compete with Twitter and/or Bluesky and is planning build an app using the the ActivityPub protocol, which is what sites like Mastodon and Lemmy use to communicate with each other. Basically the idea seems to be that Instagram users will be able to communicate with the rest of the Fediverse.
Two weeks ago, it turned out a couple of mods of the larger instances had had secret (!) meetings with Meta. In a reaction, a group of instances decided to start a pact to preemptively block Meta.
The shocking news this week was that a couple of admins of large Mastodon instances were talking with Meta (under NDA's!), so it seems your hope (and mine) will be in vain.
Thruth.social was actually never part of the Fediverse. It does use AcitivtyPub, but it doesn't federate with other instances: https://pocketnow.com/trump-truth-social-network-removes-most-freedom-friendly-features-fediverse/
Good news for scammers
On Mastodon there was this whole thing about users calling themselves Twitter refugees, and people expressing their displeasure with the term. It does feel a bit inappropriate to equite youself with actual refugees. We're just moving from website to another.
These mods signed NDA's in order to meet with Meta. This means they cannot share what was discussed. This is one of the reasons there are so many rumours about Meta's plans and how these meetings fit in.