On top of that, since iOS 11 (or maybe 10), trusting a USB device requires the passcode by default, so even having your phone ripped out of your hands unlocked does not lead to the ability to take a USB backup directly anymore.
I haven't looked into this so I apologize if it's an easily answered question but... is this (MDM/ADC) something an individual can do for their own devices? I know it can be done at the organizational level for, e.g., employer-owned devices, but how hard is this for Joe Blow to set up for, say, his kids' iPads and iPhones?
A few warnings:
1 - Changing an iOS device to "Supervised" will wipe it (so you can't supervise someone else's device and data).
2 - Backing up iOS devices over USB after requires that you keep the keypair, and makes restoring to new devices much more complicated. I would not recommend relying on USB backups if using this method unless you play around and understand it well.
3 - Be sure you set the profile to be removable only by wiping the device, or using Device Configurator, otherwise, the profile could be deleted to enable USB.
4 - One could wipe the keys completely to be sure that NO machine has USB access to the phone, meaning it would need to be restored to factory defaults for USB to work again.
https://blog.rapid7.com/2015/11/26/reduced-annoyances-and-in...
(Granted, my strict needs could be met with one of TI's sub-$0.50 microcontrollers and a seven-segment display since they're "make phone calls" and "generate two-factor authentication codes")
If all you need is enough to run a TOTP app, you could get a dumb phone with a $10 token but you could also make an honest comparison with the $350 iPhone SE or $450 iPhone 6S rather than comparing the iPhone X/8 to devices which weren’t intended to compete with current generation flagship models.
Android handset makers just manufacture the handset. Google provides the OS, and the underlying services for the Android ecosystem.
Apple bears both the cost of handset manufacturing, and the entirety of costs for the smartphone's ecosystem. That cost is reflected in the price, making the markup less "insane."
The Chinese handset makers in question may provide their own software, but it's typically considered "bloatware" and no where near the quality of software that Google provides.