Select multiple entities to link their on/off state. If any selected entity is turned on or off, the other selected entities will be sent a matching on or off command.

link_multiple_devices_invert.yaml

blueprint:
  name: Inverted Link On/Off State of Multiple Devices
  description: |
    If one entity turns ON, all others turn OFF.
    If one entity turns OFF, all others turn ON.
  domain: automation
  homeassistant:
    min_version: 2022.5.0

  input:
    linked_entities:
      name: Entities
      selector:
        entity:
          multiple: true

mode: queued
max_exceeded: silent

variables:
  linked_entities: !input 'linked_entities'

trigger:
  - platform: state
    entity_id: !input 'linked_entities'

condition:
  - condition: template
    value_template: "{{ trigger.to_state.state != trigger.from_state.state }}"
  - condition: template
    value_template: "{{ trigger.to_state.state in ['on','off'] }}"
  - condition: template
    value_template: >
      {{ trigger.to_state.context.parent_id is none
         or (trigger.to_state.context.id != this.context.id
         and trigger.to_state.context.parent_id != this.context.id) }}

action:
  - service: >
      homeassistant.turn_{{ 'off' if trigger.to_state.state == 'on' else 'on' }}
    target:
      entity_id: >
        {{ expand(linked_entities)
           | selectattr("entity_id", "!=", trigger.entity_id)
           | map(attribute="entity_id")
           | list }}