Fun fact, Google allows end to end encrypted backups, but Apple - due to pressure from the FBI - decided to keep access to your iCloud backups.

https://www.reuters.com/article/us-apple-fbi-icloud-exclusiv...

So if you use their cloud services, both Apple and Google have access to your photos, but Apple has access to all of your whatsapp and signal conversations, while Google does not (if you decide to password protect your backups).

And you have to use iCloud if you want to keep your 3rd party chat history safe, unless you jailbreak to extract it from the file system.

iMessage is of course purposefully flawed to allow for MITM.