As long as it’s not literally every single source of electricity a node is connected to, Bitcoin would be fine

What happens to your bank account, communications systems, or health services? What about your water and food supplies?

That would be the real issue in that scenario

If the electric grids go down for any meaningful amount of time, the last thing you’ll be worrying about is bitcoin.

Unless its something nasty like a solar storm that wipes out all electronics. There plenty of operations running on self powered mode. Gas, solar, wind and water. Ill personally crank on some dynamo or someshit if the hashrate drops to near zero.