Wifi Device Counter?

Looking for a device that will report how many wifi (or possibly bluetooth or cellular) devices are in the area to the smartthings hub. just need a count, don’t need to know anything about them.

the use-case is for monitoring occupancy for my rental home. more devices in the area, or a spike in device count are a good indicator of the number people in the home. that (along with non-listening noise level detectors) can alert me to place a call to the home/check it out to help keep out parties and be more respectful of neighbors.

here’s some code that does it with a $15 usb wifi adaptor. perhaps on a rasberry pi then integrated to smartthings?

would rather buy then build though.

The google WiFi router can connect to IFTTT and take action if a specific device becomes active on your WiFi. You can also see number of connected devices.