

I don’t know what an app bundle consists of, which the page you linked says google needs, but it can’t include the source code because google has recently been paying some developers for access to their source code - https://www.techrepublic.com/article/news-google-android-code-offer/
In any case, having access to the source code will not grant access to encryption keys or allow anyone to decrypt messages. After all Signal is already open source so anyone can use the Signal protocol for encrypting messages, which is exactly what WhatsApp does.




I think this tells us all we need to know about proton unfortunately.