Here’s how WhatsApp plans to interoperate with other messaging apps
https://www.theverge.com/2024/2/6/24063705/whatsapp-interoperability-plans-eu-dma
Here’s how WhatsApp plans to interoperate with other messaging apps
https://www.theverge.com/2024/2/6/24063705/whatsapp-interoperability-plans-eu-dma
IIRC it wasn’t the signal protocol, just the encryption methods that were shared with WhatsApp. I don’t think federation was ever on the cards.