I don't know if this quite meets your specs, but we have battery backups on a lot of our electrical equipment that can let it run for several hours during an outage. These are significantly cheaper than a powerwall ($150-$500ish)

This means that we can still have wifi/internet (fiber often stays up during an outage) even if we don't have power.

We were out for several hours, but for us the only difference was the lights. (woodstove heat)