Home assistant and Mitsubishi via https://github.com/SwiCago/HeatPump

configuration.yaml

# Assumes you have a topic structure like: heatpump/<room> and heatpump/<room>/set 
# E.g. heatpump/bedroom, heatpump/bedroom/set, heatpump/office, heatpump/office/set
#

# Configure the MQTT HVAC climate platforms (Example for master bedroom, office and nursery. Change to suit.):
climate:
  - <<: &mitsu_platform
      platform: mqtt
      modes:
        - "off"
        - heat
        - dry
        - cool
        - fan_only
        - auto
      fan_modes:
        - AUTO
        - QUIET
        - "1"
        - "2"
        - "3"
        - "4"
      swing_modes:
        - AUTO
        - "1"
        - "2"
        - "3"
        - "4"
        - "5"
        - SWING
      current_temperature_template: "{{ value_json.roomTemperature }}"
      temperature_state_template: "{{ value_json.temperature }}"
      swing_mode_state_template: "{{ value_json.vane }}"
      fan_mode_state_template: "{{ value_json.fan }}"
      mode_state_template: >
        {% if value_json.power == "OFF" %}
          off
        {% elif value_json.mode == "FAN" %}
          fan_only
        {% else %}
          {{ value_json.mode|lower }}
        {% endif %}
  - <<: *mitsu_platform      
    name: "Office A/C"
    current_temperature_topic: "heatpump/office/status"
    temperature_command_topic: "heatpump/office/_set/temperature"
    temperature_state_topic: "heatpump/office"
    swing_mode_command_topic: "heatpump/office/_set/vane"
    swing_mode_state_topic: "heatpump/office"
    fan_mode_command_topic: "heatpump/office/_set/fan"
    fan_mode_state_topic: "heatpump/office"
    mode_command_topic: "heatpump/office/_set/mode"
    mode_state_topic: "heatpump/office"
  - <<: *mitsu_platform
    name: "Master A/C"
    current_temperature_topic: "heatpump/master/status"
    temperature_command_topic: "heatpump/master/_set/temperature"
    temperature_state_topic: "heatpump/master"
    swing_mode_command_topic: "heatpump/master/_set/vane"
    swing_mode_state_topic: "heatpump/master"
    fan_mode_command_topic: "heatpump/master/_set/fan"
    fan_mode_state_topic: "heatpump/master"
    mode_command_topic: "heatpump/master/_set/mode"
    mode_state_topic: "heatpump/master"
  - <<: *mitsu_platform
    name: "Nursery A/C"
    current_temperature_topic: "heatpump/nursery/status"
    temperature_command_topic: "heatpump/nursery/_set/temperature"
    temperature_state_topic: "heatpump/nursery"
    swing_mode_command_topic: "heatpump/nursery/_set/vane"
    swing_mode_state_topic: "heatpump/nursery"
    fan_mode_command_topic: "heatpump/nursery/_set/fan"
    fan_mode_state_topic: "heatpump/nursery"
    mode_command_topic: "heatpump/nursery/_set/mode"
    mode_state_topic: "heatpump/nursery"


# MQTT HVAC uses individual command topics but HeatPump does not
# so use an automation to push the commands to the HP (only one automation needed due to wildcards):
alias: 'Redirect all MQTT HVAC set commands to the heatpumps'
trigger:
  - platform: mqtt
    topic: heatpump/+/_set/+
action:
  - service: mqtt.publish
    data_template:
      topic:  '{{ "heatpump/" + trigger.topic.split("/")[1] + "/set" }}'
      payload: >
        {% if trigger.topic.split("/")[-1] == "mode" %}
          {% if trigger.payload|upper == "OFF" %}
            {"power":"OFF"}
          {% elif trigger.payload == "fan_only" %}
            {"power":"ON","mode":"FAN"}
          {% else %}
            {{ "{\"power\":\"ON\",\"mode\":"|safe + trigger.payload|upper|tojson + "}" }}
          {% endif %}
        {% else %}
          {{ "{" + trigger.topic.split("/")[-1]|tojson + ":" + trigger.payload|tojson + "}" }}
        {% endif %}

If I was to set this up now, I would probably use one of the following which both support the MQTT climate integration natively:

https://github.com/unixko/MitsuCon

https://github.com/geoffdavis/esphome-mitsubishiheatpump