Privacy centric messaging apps like Signal don't work either and that's a real shame because the iPod touch is inherently more secure than the iPhone.

Came to say the same thing: Shame that one can't run WhatsApp or Signal on them, would be an option for grandma to keep at home.

(Note: not Apple's fault - iMessage, Wire, and other messengers work, if I'm not mistaken.)

Identification and authentication by phone number should die (or at least be an option among several).