I’d not bother using stored electrical energy to cope with power outage, the inefficiencies stack up.
I’d simply use stored negative energy, i.e. have a top-loaded highly insulated freezer and have it totally full. Items you intend to eat first stored around the outside and the middle will stay frozen for a long time. If you don’t want to waste expensive food then simply make ice and pack that around the outside, let it melt slowly instead.
The front door type, every time you open it the heat from outside pours into the top and the cold pours out the bottom. They are more convenient for regular use in kitchen. We had a front loading and a top loading and all the expensive food in the top loading to survive power outage.
In August and September I spent weeks living out of a cooler box and bought a block of ice every third day and items like milk didn’t go off at all, the ice slowly melted, kept contents just above freezing and I drained the meltwater away and bought a new ice block. The same principal for a top-loading freezer will last even longer.