If I sell Iphones and want to steal data, I write & install and app that does it for me. Simple, no hw needed. If I want to extract from a stolen/bricked Iphone, I rip out the flash memory and read it directly using electronic circuits. No apple sw in my way then.
You think you're smart. Anyone with an iPhone will set their Apple ID and password, and the process of doing this wipes out any software that you may have installed. The exception is phones sold to enterprises, where the process will wipe any software you may have installed and put the phone under the control of the enterprise. Very visibly.
To decode the flash memory, you need to crack per-file 256 bit encryption. So even if you cracked uncrackable 256 bit encryption, you would then have _one_ file.