@fediversereport Worth Noting:
1. During the "earlier" days of the "Federation", it was possible to "semi"-Federate with Facebook. Their chat used the XMPP protocol and thus one could chat with their Facebook contacts, as well as any other contacts they may have that used the protocol. Facebook also allowed means of both pushing and pulling post via their API....
In the "Federation", there was a time when it was possible for Friendica, Hubzilla, and to a more limited degree, Diaspora pod/server accounts to not only Federate across their own open source and decentralized protocols, but to essentially bridge incorporating interactions with the major platforms, including Facebook.
(If memory serves correct, Facebook killed off XMPP for chat AND the bridging capabilities sometime around 2012-2013)

2. Facebook (Zuckerberg) contributed to financing development to (at least) the Diaspora Federation Protocol.

*IMHO, while Diaspora directly addressed many western populist pop culture ideas at the time of it's birth, it's inability to deliver a user experience that didn't "feel" isolated from the majority of ones more direct friends/family/community, led to lack of adoption and subsequent non-threat to the major social nets. What @heluecht worked out with Friendica/Hubzilla however, notably when coupled with things like XMPP, created a situation where if Facebook/Meta NOT killed of XMPP and cut down on their provided API abilities to facilitate a bridged experience, the major social nets as they are currently known very well may have had major threat issues on their hands if not outright collapsed within a few years.
@Gargron Mastadon/AP surge (much like the "PlusPora" Diaspora pod instance the past) stands as a rather unique (and odd) occurrence in the Federations history, but Enterprise working in cooperation with and facilitating bridging to the Federation is more a return of progression from the 'earlier' days than something totally new.*