[omnicognate]

On iOS you don't have root. This prevents you doing many things with it, which is why jailbreaking exists. The fact that you can write an app and deploy it directly to a restricted number of devices for testing (if you're on the Apple Developer Program and own a Mac) doesn't change that.

Try altering the iOS home screen behaviour, directly accessing the filesystem, writing your own device driver or tweaking the kernel. You certainly don't have "bare metal access" except by voiding your warranty and risking bricking your device by jailbreaking it, if there even is a jailbreak exploit that currently works on your device.