It sounds like they won’t
I found another method that uses the cast feature. https://www.youtube.com/watch?v=WYdvZVI7KFA
If you follow the instructions in the first link, it will tell you how to make your Google Home devices into speakers. There is a smartapps on the app which has a few sounds already in it, and it has a TTS function. I’m using the method in the video so I can take any MP3 I made and have it play through the speakers. When I get time, I will try to get the thing to work with WebCore instead of IFTTT to quicken things up.
BTW one thing I didn’t put in the video. I’m using the app I was referencing above to tell me the weather in the morning. Basically, when a given motion sensor finds me walking around first in the morning, it will play the weather in any Google Home device I want. I have it where it plays only1 time.
Basically I have a virtual switch which can be triggered on by giving motion sensors during x and y time. This has to happen from an off state (otherwise it will keep playing the weather).
Then when the time gets to y, the system automatically makes the switch off so it’s ready for tomorrow.
So what triggers the sound is the switch going into an on state.