Take a look at behind-the-switch relays.. I haven't had much luck with the Z-Wave dual ones (Qubino, Aeotec) though but things may have changed.
Shelly WiFi looks interesting and I think there are community drivers available but do not know the details.
Also seeing stuff ZB 3 stuff like the Tuya Relay - also cannot comment as to whether this is decent or not.
Keep in mind if your gangboxes are metal that may impact the signal as well..
I understand that Inovelli has Zigbee switches in development, but nothing released yet. I would also echo @erktrek's advice to look at in-box relays. I've used the Sonoff ZBMINI (single-device) successfully, and the recommended Shelly 2.5 is a similar function except that it is WiFi LAN connected and can control two devices. Neither of these is UL listed (ie. not certified as US code compliant) and that is a deal-breaker for some people.
An alternative to dual-gang switches would be to put the "smarts" in the fixture using these in-box relays and use a "dummy" switch on the wall. The Lutron Pico remote is a very popular and inexpensive option for this, but that might not be the simplest option when using a zigbee relay as the controlled device. Although if you end up using lots of Pico's their low-cost can offset the added cost of the bridge.
I would also comment that z-wave doesn't always have problems. I've had a Zooz dimmer and Zen16 operating flawlessly for over a year and have recently added 6 more Zooz devices (two Zen17s, two more ZEN16s, a Zen32 Scene Controller, and a smart plug. No issues so far. If you do decide to try this out, I would go slow and easy, and start with a Zooz ZEN30. Its a zwave dimmer/switch combo unit that is meant for just this type of install. I think this would be my first option if I were in your shoes.
Thanks I will look into it.. Just starting my research, so thought I'd check with this group as you've had great insights in this thread.
Thank you. I will look into zooz. I have a large home and was concerned by the comments that having to make several hops over repeaters with zwave may be trouble. Assumed a large home I'd encounter that issue. Learning as I go 
Such as?
https://www.aliexpress.com/item/32987793126.html?spm=a2g0s.12269583.0.0.65003f25pMW1UV
Based on these messages posted earlier here ....
keep reading that thread, that device most certainly didn't get zigbee certification that I was able to find...
Other confirmed Zigbee 3.0 certified devices that aren't working with Hubitat right now?
Not trying to be an ■■■ here, i'm very much interested...
The problem with this approach to my mind is that if your automation system fails, you've lost absolutely all control. At least with a regular zwave (or indeed zigbee) switch or dimmer you might lose automation control through the hub but the wall switch will still work as a last resort!
The point about wiring code requiring EMT is interesting - I assume that also implies metal wall boxes?
Everyone's idea of large is subjective, but for reference, my home is 1250 Sq. Ft each on the main floor and basement. Upstairs is 950. My devices just happen to be in adjacent rooms, more or less. Although I do have some in my detached shop. Zigbee devices worked with almost no planning or effort. Zwave needed some well placed repeaters.
https://community.hubitat.com/t/moving-new-house-has-detached-shop-signal-range/77497/20?u=dylan.c
Hi yes, the eboxes are metal as well. It's really overkill for residential, but is a requirement the town places on new construction. You can at least use MC whips for final 2-3' if I recall. Even MC cable was against code. So basically you have to plan right the first time. And well who knew. I also had component wires run everywhere to distribute video--right before HDMI came to market. WOulda coulda shoulda... had I known.. Thanks for everyone's inputs.
Old wires make good pull cables for running new wires.
Have you considered Lutron Caseta. You can put a pico side by side with a box so that you do not have to expand the box. This may not work for all cases but it might work for some. Lutron is not Zigbee or Z-wave but it is extremely reliable. I have always had a very reliable experience with Insteon (Dual Mesh only). Unfortunately they had discontinued the serial PLM so the ISY and Insteon is no longer an option.
Lutron Caseta with Zigbee motions, sensors and plug sockets is a very reliable solution out there. Of course with your Hubitat
Hi, thank you. Yes I've considered or looked at Caseta, as I know Lutron just works.
Do they provide a hidden switch option? where by I could connect the extra wires that I have going in to my single gang boxes today to support the double gang switches it was wired with.
All I've seen from lutron are single single per each gang box, so I'd need some way to connect those wires to a hidden switch then just use the pico to control that but remotely.
Thanks!
No they do not but you can use a Zigbee hidden switches and control them with a Pico.
Here is an example.
Here is another example.
ah ok. so for signalling use caseta and zigbee for the hidden switches, and obviously hubitat to cross pollinate the messaging. thank you. This is exactly what I needed to find. I was only finding zwave ones..
I haven't had good luck with either Zigbee or Z-wave devices. I'm thinking about switching a lot of my problem devices to Lutron to see if that fixes the issue. Only other thing it could be is Hubitat itself at this point...
Just make sure you get the Caseta PRO hub. The regular Caseta hub will not work. The good news is all the integration is via telnet and stays local.
This is the one I got - I think it's the Caseta Pro. Got it May 2020:
Download the Hubitat app
