I love my Home Assistant setup for this reason. I can even get light bulbs pre-flashed with ESPHome now (my wife was bemused when I was updating the firmware on the lightbulbs).
This is an absolute requirement for all of my smart home devices. Not only in case of an outage but also in case the manufacturer decides to stop supporting my device in the future. My Roomba, litter box, washer/dryer, outlets, lights, and all the rest will keep working even if their internet functionality fails. I would like all of those devices to keep working for at least a decade, and I'd be surprised of all the manufacturers keep supporting that old of tech.
My lighting automation uses Insteon currently. My primary req is that they are smart and connected without needing a central controller o a connection to the internet. My switches all understand lighting scenes and can manage those in a P2P manner, without a central controller. The central controller is primarily used when I want to add actual automations vs. scenes. Even the central controller aspect works 100% disconnected from the internet though. I can easily layer on top any automations I like. For instance, I have my exterior lights driven my the angle of the sun. Then, on top of that I can add internet based triggers for automation as needed. This is where I add in voice assistant triggering of automation and scenes.
Edit:
Just to add, very simple binary automations are even possible without a central controller. Like, I have Insteon motion sensors that trigger a lighting scene when they detect motion. These are super simplistic though.
