Hopefully someone has something like this working and can tell me how they did it. I have a light switch (smart, you pick the model) and a smart light bulb (sengeld color zigbee).
Basically, I want these things:
a wall switch that, when pressed, turns on/off the light regardless of hub function. (ie, a physical power switch). This is for safety, coding, common sense, visitors, etc
a way so that if the smart bulb was turned off by the hub, depressing the light switch will turn the lights back on.
a way that if the light switch was powered off, I can turn the smart bulb back on via the hub.
My thought was to make a few rules that basically say:
if the switch was turned off, wait a moment, turn the switch on, and turn the smart light off
if the switch is pressed (ie, to turn it on, even though it already is on because of rule 1), check to see if the smart bulb is on... if not, turn it on.
This should work with the Leviton decora switch using the "physical switch" trigger but apparently does not. Is there another, better way of doing it?
There isn't a great way to do this with most smart bulbs on circuits controlled by a smart switch, but any of the options you describe should work. But there are some additional things you could consider.
If you aren't attached the idea of a hard-wired smart switch for any reason (e.g., you want a Z-Wave repeater there and this is how you're doing it), you could use any switch--smart or not (but for price I'd probably go "dumb")--and do something that would give a similar effect. The options are basically covering the switch and using something else, though some are "functional" switch covers that provide buttons you could use. A couple ideas...
If you don't think it's ugly, you could get a light switch cover like these for toggle switches or similar ones for decorator switches, then use a button device nearby. Good ones I can think of include a Pico Remote (if you have a Lutron bridge) or Hue Dimmer (works natively with Hubitat if you want); the first can mount in a standard decorator plate, while the second can't but does come with its own (optional) wallplate.
You could also just cover the existing switch with the Osram dimmer remote, which attaches over an existing toggle or decorator switch or the similar CentraLite dimmer remote (actually never used that but looks so similar to the Osram/Lightify that I can't help but wonder if they're the same except for branding). Unlike the above options, these cover the switch and replace it with functional buttons (rather than you needing to find a way to mount a different device in an intuitive location).
If you really do want a smart switch, your best bet is probably to:
Use a Z-Wave switch that supports disabling the internal relay. (When you truly want to turn the circuit off, you can re-enable the relay; otherwise, it will just send events to Hubitat that you can use in automations, but the switch won't affect the circuit.) The enabling and disabling of the relay can be done via physical actions on the device or setting a Z-Wave parameter. Inovelli are the only switches I'm aware of that support this, though they're currently out of stock (might be able to find a refurb or used). There may be others. and hopefully they'll be in stock soon, assuming their new supplier/hardware will also be able to support this.
See if subscribing to the "on" event for your bulb happens to work when its circuit (smart switch) is off, in which case you could also subscribe to that event in a rule (or app), then check to see if the smart switch is on and turn it on if not. Not sure if this would actually work with your bulbs.
Do something like what you suggest--it's not ideal, but could work. It's basically what I do, though my goal is to never actually turn the smart switch off. As a safeguard in case someone does, any automation that turns this light on also checks for the smart switch and turns it on if it's not already. Unfortunately, you'll probably have to wait a few more seconds after this (for it to be back on the ZigBee network) if you want to send additional commands like color or level, which will complicate things, but it's certainly possible. I don't do that since I'll settle for the bulb's default after-power-loss state.
As an alternative to disabling the relay (or if your switch doesn't support it), some people may suggest a solution like connecting the line and load wires. The switch will still send on/off events, and you can use them in automations (e.g., to change the bulb), but it won't actually turn on/off the circuit. This, of course, is not really what you want but could work if you're willing to settle for there still being one way to turn the socket/circuit off should you really need it: the breaker.
Was just searching around tonight to see how many other brands had an option to disable relay like Inovelli (due to them being unavailable). I am surprised that it is unique to the Inovelli lineup. Myself it just makes sense, if I'm going install switches they should be multi purpose. To start many places I want dimmers for dim defaults at night, but later when I have more RGB bulbs I might want a red dim mode at night or colour alerts. If I can change a setting in switch instead of adding or changing hardware that's a huge benefit.
Only place I have found talk by a switch maker is in the HomeSeer HS-WD200+ and HS-WS200+ Firmware Updates thread Here. The HomeSeer rep in thread was not very receptive, saying it is to much of a niche usage to bother with, unless they starting hearing from more people wanting such a feature. Many folks chimed in also wanting a switch that will work for dumb bulbs, or smart bulbs.
I'm not clear on why you would need the switch AND the bulb to be smart? I use Shelly hard wired wifi switches wired right into the switchboxes with a dumb switch and I believe it meets all your criteria above.
I believe the only difference is I have to turn off the switch, then back on to overrule the previous command from the hub.
Zooz has announced that newer firmware on some of their newer (maybe more?) switches now also support disabling the relay on their switches/dimmers or will with an upcoming firmware update. Ask their support if you want one and aren't sure. Inovelli should start shipping later in July, but I recently discovered the announcement from Zooz.