Also, iMessage is very secure...but then all your stuff is backed up on iCloud servers unless you specifically disable it. That includes all your iCloud encryption keys and plaintext messages.
Worse, iPhones immediately start backing up to iCloud when set up for a new user - the only way to keep your network passwords and all manner of other stuff from hitting iCloud servers is to set the phone up with no network connection or even a SIM card installed.
Did I mention there's no longer a SIM slot, so you can't even control that?
And that iPhones by default if they detect a 'weak' wifi network will switch to cellular, so you can't connect the phone to a sandboxed wifi network?
You shouldn't have to put your phone in a faraday cage to keep it from uploading plaintext versions of your private communications and network passwords.
iMessage only encrypted messages in RSA 1280, why do you think it is very secure?..
Good luck for us all being „independent”. We can make processors out of attached plastic bottle caps…