There was a 4-day power outage here (Seattle suburbs) last fall, and one of the auto parts store made an effort to serve customers even though they didn't have any power. I paid cash, and I forget whether or how they did credit card transactions (possibly by writing down CC numbers on paper.) They made a lot of phone calls to a different store to get prices for items.

They can and do. They will also do deep cuts on prices/give away for free for refrigerated and frozen goods because those will just get tossed and neighborhood goodwill is still a thing in some places.