You dont have to register for ios and android. For sure not with you real data. Anonymous email suffices. And you do get services by both platforms for free included in your purchase. Push notifications, automatic updates, free messaging and not to speak about tons of free apps to use.
I believe you no longer have to register your ios device - but it is a dark pattern. On the screen to enter your apple id, you don't have a "skip" choice, you have to say "don't have one" and I believe then you can skip setting up an apple id.
You can use it like a phone at that point - you can send text messages and make calls, but I don't believe you can install any apps.
That said - you must go online - turn on cellular data or wifi before you can use the phone, it must be "activated". And apple phones home a lot.
On a mac run little snitch. On a current ios iphone, I'm uncertain but i run an older version of ios with adblockios.
It contacts a whole slew of apple and 3rd party sites. the main one is that it contacts *.ls.apple.com all the time (location services) even with location services turned off. lots of other apple sites. third party is akamai all the time, but also sites like phicdn.net and att.net (I have an at&t iphone). I do not have any at&t app installed.
on macos catalina, you can (currently still) run little snitch and all kinds of services start contacting apple. and new ones have shown up like touristd and rapportd. Every time you try to pull up a help page. Every account you configure, apple based or not. sigh.
I wonder whether the ls.apple.com servers are connected with security features like "Find my iPhone". But then, I'm not sure exactly what Find my iPhone does if it's turned on but location services are disabled.
