If I had the disposable income to purchase an effective handheld cell phone jammer, I would. I believe the better ones also "disable" GPS
devices. Re: GPS... if you do not know where you are going
AND how to get there
BEFORE you leave the house, then please just stay home. Or print directions from one of the hundreds of mapping sites on the internet.
I do have, and carry on my keychain, a little doohickey that will turn off televisions. It comes in handy, on occasion, when we are seated near a 52" display in a restaurant where the volume is up to 11.