When sized correctly (and configured with proper non-essential load-shedding), whole home batteries can keep freezers and refrigerators running for days. Sometimes, they're even enough to keep your a/c or furnace going for a good bit.

Using batteries like this is great in places like Vermont or the PNW because of how many trees there are. I live in the PNW, and we get frequent outages from trees falling on lines. Normally, tree-related outages only last for a few hours at most, so these systems cover that gap.

There's another benefit for the power companies, in that they can have residents feed partially from the batteries during high grid stress. That helps to lessen the load on the rest of the power infrastructure.

So yes, when they're not fed for awhile, you'll still lose power. Overall, though, you'll experience less time without power since these will cover the shorter, more common outages.