Revolt had us all intrigued, but without federation, it's like a pizza without the cheese.
Enter, Matrix and Element - FOSS, decentralized, and yes, federated.
Element, built on Matrix, provides real-time communication with end-to-end encryption. But voice channels, alas, still our Achilles heel.
Yet, remember, we're the pioneers of this brave new digital world. A federated voice solution may not exist now, but give it time. We've got some amazing and selfless coders chomping at the bit!