I had both catalytic
I had both catalytic converters stolen from my 2014 Prius outside my house in the middle of the night in Dallas, TX. They didn't even need to break into the vehicle, they just lifted the front of the car and towed it off to another private location where they cut out the converters, which also caused body damage to the front. Since you can cut through sheet metal pretty easily with a battery-powered reciprocating saw, I doubt a shield would have helped in my case. I'd still consider one though given it's fairly cheap and may helped when I'm parked out in public elsewhere.