That would work 100% and no crazier than having the TV tell your Google Hub to turn off the TV. I used to have my Echo sitting next to my Google Home Hub to tell it to set the volume level at different times of the day. They still don't have anything comparable. You can adjust assistant volume per time of day, but not a per device volume like you can with Echo.
Google home is a nice touch screen for your smart home control, but beyond that it's just pathetic how little they have accomplished versus what Amazon can do with Alexa.
There's lot's of differing examples of this code. All fairly similar. This one turns off in 12 seconds. You can just modify that number on the runin line to change how long you want it to be on before turning off automatically. There's a few better examples after my post, but this works just the same. Just need to trigger it manually the first time to get the default state.
You then just create and Alexa routine and have her speak the custom phrase you want on your Echo. As the trigger for that routine, you select the custom "Motion sensor as a switch" device you created that used your custom code as its driver. So anytime that switch is turned on from Hubitat, Alexa will think a motion sensor was triggered and since you set that virtual motion sensor as the trigger for the Alexa routine, it will speak your custom phrase.
