Why phone? This cuts out a lot of phones. Why not on a computer?

I used to red team professionally, and it is a lot easier to sneak an unauthorized phone into a facility than a computer.

Agreed. Also less noticeable when "accidentally" dropped/left, especially in tight spaces out of view. And better odds of plausible deniability if caught or device is later found and somehow traced to you.

Many kids don’t have a computer

Are kids the target audience of this tool?

Yes