Messenger never used XMPP and never federated. They had a half-baked gateway to allow third party clients for awhile as an experiment, but that’s all they ever did.

As a client developer, happy to hear feedback on existing clients and what you think is needed for ‘good’

Still does

luckily neither of those things was destroyed and both are alive and well 🙂

Snikket if you want simple, or prosody if you want flexible.