Mighty said:What issues has your friend run into? Is there anything he's wanted to do and couldn't, because of the lack of a neutral? Is there anything he's wished for that's not conveniently supported by the Caseta system, so he feels locked in?
Tonight, a guy on the openHAB forum says that he has been working on a binding for some Zigbee USB dongles. Said he plans on getting back to actively working on it in a few weeks. I'm trying to get more info from him on whether some of the specific examples I've seen on Amazon will work.
The solution in place is tied to HomeKit, so this is a binding constraint. My friend does not wish to have complex automation rules or integration with other technologies, so this setup works well. I have not tried the Lutron's pro hub that claims to integrate with some other systems (like Elk).
Over the years a lot of people claimed they were working on zigbee integration. The result is always the same: at best, SOME dongles will be able to control SOME devices. Unless you can code and willing to reverse engineer the zigbee messages, it will be very restricted.