Yes, this add on doesn’t replace any component in the ecosystem except the tts component.
All it does is create a standalone google assistant inside the add on, and that assistant accepts text-based queries… letting you broadcast text to all your google home devices using any type of automations that would send text notifications.
The quality is not only staggeringly better than the normal google tts in home assistant, but it will not cancel music that is playing on the google home.
If you do not have google home devices, than this add on won’t be of use to you. You won’t get any broadcasts.
Also, the google home you have must be using the same google account that you use to authenticate this add on.