How to get TTS announcements without interrupting Google speakers that are already being used.

ghm_tts.yaml

# ghm_tts:
  alias: 'Google Home Notifier'
  sequence:
    - service: media_player.volume_set
      data_template:
        entity_id: >-
            {%- set players = ['media_player.kitchen_home', 'media_player.lounge_home', 'media_player.bathroom_speaker', 'media_player.ensuite_speaker'] %}
            {{ states.media_player | selectattr('state','!=','playing') | selectattr('entity_id', 'in', players) | map(attribute='entity_id') | join(', ') }}
        volume_level: '{{volume}}'
    - service: tts.google_say
      data_template:
        entity_id: >-
              {%- if states('media_player.kitchen_home') != 'playing' and
              states ('media_player.lounge_home') != 'playing' and
              states ('media_player.bathroom_speaker') != 'playing' and
              states ('media_player.ensuite_speaker') != 'playing' %}
              media_player.tts_homes
              {%- else %}
              {%- set players = ['media_player.kitchen_home', 'media_player.lounge_home', 'media_player.bathroom_speaker', 'media_player.ensuite_speaker'] %}
              {{ states.media_player | selectattr('state','!=','playing') | selectattr('entity_id', 'in', players) | map(attribute='entity_id') | join(', ') }}
              {%- endif %}
        message: '{{tts}}'

## How this works: First section [volume] looks at which media players are not playing (!=playing) and lists
## out all that aren't from the defined players list under the 'set players' section
## The {{volume}} level is pulled from the script that invoked this script and those that aren't playing get their volumes set.

## The next data template for tts.google_say looks again for media players that are not playing and if none are,
## it chooses the defined group of media players (media_player.upstairs_homes) which has to be set up in the Google Home app.
## So the broadcast will happen to all speakers in that group.
## If any of the speakers are playing, the script will instead list all media players out separately so as not to
## interrupt the speakers that are playing music. The actual text spoken is pulled from the {{tts}} section
## from the script invoking this script.

## N.B Instead of having {{ states.media_player.kitchen_home.state != "playing"}}, you can change
## this to {{ states.media_player.kitchen_home.attributes.media_content_type != 'music' }} which looks
## specfically if the device is actually playing music not just playing (anything). Of course, you can use any
## attribute you like.

## Help here https://community.home-assistant.io/t/help-creating-a-template-sensor-to-overcome-google-cast-issue/113159/14