1) You can't have any moving parts on it or the seams become a slot antenna

2) Will drain your battery as it adds power to find a faraway cell tower (unless you are in airplane mode)

3) It actually does exist. It costs $1000: https://privoro.com/product-vault

For significantly less money, one could get these - https://www.amazon.com/Faraday-Anti-Tracking-Laptops-Firepro...

I keep backup navigation tablets on my sailboat inside of those, with the idea being that if the boat is ever neutralized by lightning, at least I'll have some backups. (I also have paper charts for most everywhere I might be.)

This just looks like a hard bag…wouldn’t you need to open it to use the device? I feel the goal of the suggestion was a way to hide the device while keeping it physically accessible.