I'm not sure if this is already possible. Can I have another application initiate an action to Google Home instead of having a person initiating by talking to it? For example: I wanted to have Smartthings IFTTT asking Google Home to play something. A couple cases below:
CASE 1: If I'm home and alarm armed and front door open then Smartthings will call Google Home for it to say: Front Door Opened
CASE 2: When the presence sensor detects I arrive Google Home greets me and ask if I would like to play anything.