Autocast audio message to group of google homes

I have a raspberry pi zero with two vibration sensors to send me pushbullet notifications when my laundry is done. I want to use tasker Autonotification to read those notifications then broadcast by Autocast through my google homes the same message for when I don't have my phone on me. 

This is just one use case, i have other ideas that I'd like to Autocast audio messages to a group of google homes. 

Similar to the "Broadcast" feature natively built into the google home devices.