mitsubishi's ac/heat pumps, that have a cn105 connector (the connector is on each indoor unit; it should also work for the water tank indoor unit) can be integrated with esphome, but you have to connect each indoor unit seperatly. If you run jysty cable from each indoor unit to a central point you can use 1 esp32 for 2 indoor units. From my experience it works very well, but i have my esp on wired ethernet.

I don't have the water heater indoor unit, so that's part of my air indoor unit esphome config:

logger:
  baud_rate: 0

external_components:
  - source: github://echavet/MitsubishiCN105ESPHome
    refresh: 0s

climate:
  - platform: cn105
    id: hvac_eg
    name: "HVAC EG"

    horizontal_vane_select:
      icon: 'mdi:arrow-left-right'
      name: EG Horizontal Vane
    vertical_vane_select:
      icon: 'mdi:arrow-up-down'
      name: EG Vertical Vane

    supports:
      fan_mode: ["AUTO", "DIFFUSE", "LOW", "MEDIUM", "HIGH"]
      swing_mode: ["OFF", "VERTICAL", "HORIZONTAL", "BOTH"]

    uart_id: hvac_eg_uart

    update_interval: 500ms

sensor:
  - platform: uptime
    name: Uptime

uart:
  - id: hvac_eg_uart
    rx_pin: 5
    tx_pin: 17
    baud_rate: 2400