On your website:
Do you want to regain control over your personal and private data on your smartphone? Install Ubuntu Touch on your ...
also guarantees the users' privacy with Ubuntu Touch. No more 'forced services' that extract your personal and private data and spy on you.

I can confirm that Ubuntu Touch is really like this.

Here what I found about iOS:
https://forums.macrumors.com/threads/ios-is-terrible-about-privacy.2205813/

• iPhone and other iOS devices must always be activated via the internet during the setup process before the devive can be used. A typical offline setup of an operating system does not exist on iOS.

If Apple turns off the servers, the Apple devices are useless.

• iOS has a remote keylogger from Apple (all your keypress sent to Apple)

• iOS connects in the background with many undocumented domains from Apple (over 120 domains in over 24 hours of use).

All these things cannot be deactivated.