The obvious solutions is a federated protocol. There's no reason for Whisper or Google to be involved in routing messages except to own the system's concept of

The obvious solutions is a federated protocol. There's no reason for Whisper or Google to be involved in routing messages except to own the system's concept of identity. Trust in binaries is a harder problem, but reproducible builds is probably an important part of it. If several separate entities vouches for the binary, you have reason to believe what you run corresponds to be published source code.