The “Signal protocol” only specifies how encryption is performed, but WhatsApp and Signal have very different protocols for actually transmitting the encrypted messages (I think WhatsApp was at one point based on XMPP, vs Signal is a bunch of protobuf blobs over a websocket)

Isn't WhatsApp using some sort of XMPP sent over Signal Protocol[1]? Anyway, seems like Signal is not interested for now[2].

[1] https://www.cometchat.com/blog/whatsapps-architecture-and-sy...

[2] https://www.androidpolice.com/signal-threema-nothing-to-do-w...

I really hope I can ditch WA in the future