I'm planning to buy a new phone, and would like advice. I will probably get one of the following:

• Pixel 8a running GrapheneOS
• Pixel 8a running CalyxOS
• Fairphone 5 running CalyxOS

Either one of these phones will effectively be without warranty from the start. I can't file a warranty claim for a Fairphone 5, because they offer no warranty in my country. I can't file a warranty claim on a Pixel 8a, because I can't create a Google account.

Free open source software is important to me, and these are the free-est phone OSs I could find.

I'm planning to install Magisk to root the phone. I need adb root at a minimum. Will this prevent automatic updates?

Why do the GrapheneOS people say that rooting breaks the whole security model of Android? I can't understand this, because only a few specific apps are granted root access, or possibly only adb.

Reasons I need root access:

• I need a comprehensive backup system. Non-root backup systems skip files.
• I want to block connections using the hosts file.
• I want to study the filesystem to learn more about Android.
• I want to mess with apps' internal states.