A faraday cage is a continuous metallic material generally with an insulated material inside so that the object won’t make contact with the conductive material. It blocks electromagnetic radiation because it flows around the cage following the conductive material rather than within
Discussion
So no app then. :-)
I mean there are such things as scramblers but I’m not sure they would work for this. Easiest thing would be keeping a metal box with a smaller cardboard box inside. Just put anything you have in there while on trips. Also drive older cars that don’t have all the sensors and infotainment systems