> There are already devices sold for hikers etc that operate like this (simple SOS text messaging etc) and sat tracking of vehicles and trucks.

Yep, I’ve owned a ton of them over the years. My first was the FollowMeSpot device coming up on two decades ago. They’ve of course gotten a lot smaller, but are still definitely “thick fugly bricks” in comparison to Apple’s designs. Looking at tear downs of them, I see absolutely no way you’ll fit the important bits of one inside an iPhone case.