Like a lot of people I use TTS for sending messages/notifications across internal speakers/assistants.
This has the issue of cutting music playback short. I was surprised to see this wasn’t already a feature request but figured given the current Google Assistant component development it would be a good time to add it.
@AndBobsYourUncle has an Hass.io Add-on already doing this.
Community Hass.io Add-on: Google Assistant Webserver (broadcast messages without interrupting music)