There obviously will be no sources. I’m telling you as someone who worked directly On iMessage and Google messages.

Apple not only gives keys they often provide access with no legal requirement at all. They also DO NOT e2ee all sources they claim to depending on what regions the messages pass through to devices they end up at. There are also massive cooperation and caching going on of messaging and push notifications which access is provided to several governments. Aka as the Wyden leaks