I’ve recently bought a De’Longhi PAC EL112 air conditioner which I wanted to include into my smart home system, e.g. by automatically activating it once the temperature rises and deactivating it if there’s no need for cooling.
not sure if this will help you straight away with your De’Longhi air conditioner, but I control several Bluetooth devices in my setup with the exec binding and sending commands by using Bluetooth gatttool directly from my Raspberry Pi 4’s built in Bluetooth.
While I have many other MQTT devices, mainly self-built Arduino based devices, no MQTT is needed for this interaction.
The above mentioned exec binding solution might be the easiest, with the hard part being finding the appropriate commands somewhere online, or sniffing them out yourself.
I’ve experimented a bit, but first I did not get a successful connection to any of my Bluetooth devices. More important: I could not find anyone who has worked on De’Longhi communication with air conditioners – since I’m no expert in reverse engineering Bluetooth communication, I think I’ve to switch to a different (less nice) solution.