I can see how a device could protect from an EMP surge created by a grid connection. Is that what they're selling? But that wouldn't work to protect electronic

I can see how a device could protect from an EMP surge created by a grid connection. Is that what they're selling? But that wouldn't work to protect electronics from magnetic pulses that would induce current within an electronic device's circuits. That needs grounded shielding physically around the circuit, like a Faraday cage.