I use smart lights with smart switches in detached mode and they are not resilient to ha going down. I wish I could get smart bulb functionality (dimming, color change) with smart switches being the physical driver of them being on/off.
I’ve got some inovelli white series switches that are on a circuit with Nanoleaf thread based lights.
I’ve managed to bind them using Matter bindings, so even if HA is offline, the switches can still on/off and dim the bulbs.
No UI supports this yet (though I think HA is working towards it), but the underlying protocol support exists, and products are starting to come to market that take advantage of it.
I think it 2-4 years, it’ll probably be ironed out and working well, but if you really want it, you can have that now with matter/thread.
I think Zigbee devices also have bindings, and those should probably be a lot more mature, but I haven’t played with those yet.
Not sure about color change, but dimming works fine - I have Shelly Dimmer2 modules behind switches, paired with "dumb" dimmable bulbs. Remotely controlled by HA / Adaptive Lighting, while also working with physical switch.
One solution to this if you're using Shellies to provide your "turn a dumb light switch into a smart light switch" is the scripting it has on offer.
I have 100% Zigbee lights, and each lighting circuit has a Shelly Plus 1 with the relay in "detached" mode (so the shelly will sense the light switch changing from open to closed and send a command to HA to turn on the lights via Zigbee). Most (all?) smart bulbs have a setting for "what do I do when power is restored" and you can set it so that they come on when power is restored.
You can then create a script that uses the MQTT HomeAssistant up/down topic and if HA is down, when the switch changes position operate the relay.
It's not perfect - if you have a powercut during the night all of your lights will come on when power is restored.
