Amazon “Dashbutton” with HG

Has anyone used an Amazon “Dashbutton” with HG?
I have seen them used with other HA systems, they just check to see if the MAC is present on the network. Could the Ping program not be used as it checks to see if an IP address is present and if the MAC is present so is the ip. The “Dashbutton” is only present on the network when pressed apparently so should this not be the same?
If this worked it would be a cheap wifi button to contrail whatever you want.
Can anyone see any problems with this?