Every so often someone asks about a plug-in motion sensor or a Wi-Fi motion sensor (for greater range).
If you are using echo devices, as of late 2019 there now is one. It’s $32 and it only has very basic features and you have to use echo as a “man in the middle“ but it does exist.
Amazons new “echo flex“ is a plug-in to give you another option for echo placement. It lists at $25 but it’s often on sale, sometimes for as little as $12.50 . But more often right around $20.
The flex itself doesn’t have a motion sensor, but it does have a USB slot and you can add one (and only one) optional add-on device. And one of those add-ons is a motion sensor.
So now you have a plug-in Wi-Fi motion sensor. However, the sensor doesn’t report to anything except the flex itself. So you could only use it in echo routines. But you could definitely have it trigger an echo routine that then turn on a virtual switch in smartthings. Including a switch which was itself part of a compound virtual device that was also a sensor. So then that virtual device would be a proxy for the real sensor that you could use in any smartthings automation.
The motion sensor itself is sold separately for $15, or you can buy it with the flex, typically for $32, on the flex product page.
This could be really good for use in a garage in cold weather climates where battery operated devices tend to fail. Or an outbuilding where you need the greater range.
Otherwise, I think most people are going to prefer battery operated sensors that work directly with smartthings, but this will be a good solution for some use cases.