Echo Speaks is only for Amazon Echo devices. Alexa TTS (my deprecated integration) is also only for Amazon Echo devices.
This thread is about Google Home devices, using Hubitat's built-in Chromecast integration (beta).
I did have an early integration that utilized the Google Assistant Relay to perform TTS on Google devices. Perhaps that is what you're remembering? That code has not been touched or supported for many years now. It also required an always on RPi to run the Relay server, IIRC.
Glad to see that the OP has solved this issue! 
