“Question: if electronic equipment was turned off, would it be ok?”
In a solar storm electronic equipment will not be impacted by the storm itself. So your equipment can be on, or it can be off, plugged in, not plugged in, it makes no difference.
The power may go out, but that is it.
So it is “just” the electrical grid that is at risk? Ok, the follow on question: if we knew for certain that we were about to be hit by a massive storm, would there be a way to limit the damage on an emergency, crash shutdown basis? The functional equivalent of a giant circuit breaker, I suppose — cut the power, and let the grid go dark. It’s a mess when that happens in a major blackout, but such things are survivable. Could you do it deliberately, and would it help?