What's a good place to start learning how to add support for a new Bluetooth device (e.g. something that is not auto detected) - I'm failing to find anything useful via google (e.g. what is the Zigbee2MQTT "external definition" equivalent for ESPHome BT Proxies to HomeAssistant)?
I have several BT proxies, and I'm wondering if I can do some snooping of the Temtop C10 2nd, which is a BT CO2 air quality meter. It'd be great to have similar support to the similar Seitchbot CO2 air quality sensor that was auto detected via the BT proxies ..