Transistorized stuff will still work. Most cars before 1980 will work. Shielded electronics will still work. Bear in mind many military combat vehicles’ electronic systems are EMP shielded.
An astute prepper would put acquire spares of all critical electronic devices such as auto ECM, elec. water pump, backup laptop, shortwave radios, GPS, two-way radio sets, solar batter recharger, etc. and put them in a waterproof container and bury it under 5 feet of earth.
Or, a shielded metal container. Why would you give such bad advice?