Yes, but then you have a hard-dependency on HA for inter-network communication, which I try to avoid as much as possible (but I fail to, for a couple of subsystems).
My failure model is:
1) no electricity, everything down but fiber, wifi, HA and the doorbell (they run off an UPS)
2) internet down: no problem, you just cannot reach the home automation from outside
3) Home assistant down: zigbee devices are paired together (like buttons + bulbs) or I have physical zigbee relays controlling dumb bulbs.
But, as said, I have some subsystem not fully working when (3) happens, like a zigbee button controlling a tasmota-based fan control.
I consider it a requirement of any smart home that alternative methods need to be available during failures. Simply having other devices around that aren’t smart, like an old fashioned light bulb and physical switch to get you through until you can fix whatever is down. 100% uptime is very difficult for large, well-funded IT companies, so I don’t think it’s reasonable to expect it from these consumer-grade devices.
We survived for over 100 years by getting up and flipping a wall switch, so the risk of a few hours without smart features shouldn’t be a showstopper.
Lutron Caseta switches don’t use an open protocol and don’t seem to get much love in the fancy consumer-level smarthome space, but have been bomb-proof for reliability for me and work to turn lights on/off as long as they have power.
1) no electricity, everything down but fiber, wifi, HA and the doorbell (they run off an UPS)
2) internet down: no problem, you just cannot reach the home automation from outside
3) Home assistant down: zigbee devices are paired together (like buttons + bulbs) or I have physical zigbee relays controlling dumb bulbs.
But, as said, I have some subsystem not fully working when (3) happens, like a zigbee button controlling a tasmota-based fan control.