Some things CAN be protected from EMP. Back in the 70’s I worked on getting an AM Radio station transmitter site “Protected” per Civil Defense spec. Basically a lot of lightning arrestors and spark gaps. It’s like planning for a direct lightning strike.
The powerlines grid is the most vulnerable. Those long wires make great antennas to pick up lots of destructive voltage! USA would be broken up into small regional power centers still operating.
Solid state electronics would be mostly toast. All modern cars. Surprisingly, old 1950’s vintage tube radios would not be harmed. I am also a licensed Amateur (Ham) radio operator. Yes, I keep a spare transceiver, disconnected, and stored in a clean metal trash can along with a few other critical electronics. There are other Ham operators doing the same thing all around the country. We specialize in self-sufficient radio operations, and we would have shortwave communications networks set up in very short order.
From my experience, some of the big AM radio transmitters across the country could survive and return to the airwaves if they have power.
EMP would be a master “Reset” switch back to 1950 technology.