A growing number of instances (mainly of Mastodon so far) are signing an ‘Anti-Meta Fedi Pact’, pledging to block any instance owned by Meta in the fediverse.
I don’t know how big this will get or how effective it will be, but if you run a fediverse instance, you should take a look at this https://fedipact.online/
Ah the good old days when I had my own jabber instance but could also use pidgin to connect to Facebook and gTalk!
Granted, even when Facebook used xmpp they never federated.
Wasn’t WhatsApp originally a private xmpp too?