I’m not sure exactly what works with STHM (smartthings home monitor in the new V3 app). In the classic V2 app, you can add a light to come on When the SHM ( Smart home monitor) is tripped, so you just put your virtual device as a light in that automation. Since it is both a switch and a sensor, you should be able to include it in any automation that works with light switches.
For WebCore-specific questions, ask in the webcore forum, and the experts there will be glad to help you. 