Why no backlash for iOS and Android? We have to register to use the devices.
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.
I see this sort of claim often, but reliable information about the specifics is hard to come by. Can you share any?
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.