What Mike was referring to is that there are a number of micro devices available which fit inside the wall and give you networked control of a light fixture. You can then use them with a number of different button or switch devices to give you manual control at the wall.
An integrated device has The manual switch mechanism with a built-in radio.
But the micros are very popular for a number of different reasons. They can solve some wiring issues which the integrated switches generally don’t, and they may have some specific features that someone is looking for. For example, as it happens, there are almost no integrated switch devices for high powered devices like hot water heaters, but there are Micro solutions for those.
So you can add network control to an existing light switch either by replacing it with an integrated device or by adding a micro in the wall. Different ones will work for different people.
Slightly off topic but…
Im looking at adding smart dimmers and trying to decide between Leviton DZ6HD-1BZ Decora Smart dimmer and a GE smart dimmer. The Leviton manual says in a three-way configuration, you NEED a second leviton remote switch in the other switch location. GE seems to just use the traveler. (I should note, the current light switches are not Dimmers.) I like the Leviton features better, but cant figure out why I would need the extra remote switch, unless that was to allow dimming control at both locations, which i really don’t care about. The instructions seem to suggest its mandatory. Has anyone installed just one?
Zooz (zwave) and Lutron Caseta (ClearConnect) both have models which can use a physical traveler wire to an existing conventional dumb auxiliary switch. I think they’re the only ones, though.
(BTW, the Zooz marketing materials are incorrect in saying that they are the first switch with this feature: Lutron beat them to it by a couple of years. But I believe they are the first Z wave switch with this feature. )
Sorry just saw this! Lutron doesn’t use Z-Wave as far as we know, they use their own wireless protocol and we only ever make claims about Z-Wave technology. But maybe we mis-phrased somewhere? Can you send us the source so we can correct it. We hate false marketing