Excellent question! First off you don't leave the radio on. It's only on when you are actively trying to receive and/or send. There are several ways; one is battery packs about the size of a smart phone that will recharge the Ham radio and my cell phone if cell towers are up. I keep my 3 in Faraday bags. They will keep things charged for about a month. I do have a little generator that should work since there's no fancy circuitry in it. Little solar panels made for charging small items like cell phones and ham radios are readily available which I would keep in Faraday bag or cage. Also your car battery should be able to charge small batteries several times even if your car won't start.
Bear in mind we don't know how things will be affected. We don't know how much houses will blunt the pulse or maybe a garage. So many variables. Some people have houses with steel siding and roofing. Obviously they won't be air tight but it may be enough to insulate enough to prevent circuit boards from getting fried. That's the problem; we just don't know and it's not like we can test it without trashing all kinds of property. Then there are different levels of pulse. Again; another variable.
All good.
To resolve that concern, I bought a small dual fuel propane/ gas generator on special and I keep it in a sealed metal trash can, along with my spare radios CB, SW, and other ... and small solar chargers ;-)
Also have a tray full of rechargeable batteries
We live in the ‘country’ and have a 350 gallon propane tank in the yard. I still keep 4 tanks of propane and 30 gallons of no-ethanol gas in sealed canisters.
There’s always more to do, but we have comms and limited power handled in several ways.
P.s. I recommend Charles Chips cans as Faraday cages.