I can only do this with books. With my phone I am too focused on the phone to work in two visual modes at the same time, which I guess supports the claims.
I also attached a laptop to a treadmill at home, but the static electricity from the rubber mat kept zapping the laptop.
The best result was a laptop on an exercise bike. But the bike couldn't have a high resistance or I would lose concentration.
Nathan Fielder wears something like this in The Rehearsal. Google tells me it is called Connect-A-Desk.
Still have complete awareness of your surroundings but still be able to read.
I'd argue that's a much more useful "killer app" than recording everyone around you without their consent.
Honestly, it's never seemed hard to me and I don't remember a time when I was not able to walk while reading without bumping into things. Even as a student when studying for exams, I'd walk around in circle in my room reading my textbooks, for some reason walking helped to better remember...