Brid Air Purifier: Developing a new platform?

I just received a Brid Air Purifier. The jury is still out on whether or not this is a good product or not. It is HomeKit compatible. When you pair it with HomeKit it appears as an Air Quality (Inferior/Poor/Good/Excellent) sensor, C02 sensor, temperature sensor, and humidity sensor. You are also given an on/off switch to turn the air purifier on or off. My gripe is that the purifier supports 4 different operating modes (off, smart, boost, night) but within HomeKit you only get an on/off switch that simply toggles between off and ‘smart’ modes. I would like to be able to set the specific operating mode programmatically.

So I’ve been trying to integrate it into HomeAssistant. Using the homekit_controller component it recognizes the temperature and humidity sensor out of the box. I managed to create an air quality sensor to bring in the Inferior/Poor/Good/Excellent air quality values as well as the CO2 levels. That was just implementing parts of the HomeKit protocol so I think they could be submitted as a pull request to that component’s maintainer. Now I want to create a service to toggle between the 4 different operating modes, something that HomeKit doesn’t do natively. I discovered that the Brid exposes an additional HomeKit characteristic called ‘Mode’. You can set it to one of four values to control the mode like I want to do, however the reason HomeKit doesn’t support this natively is because this particular characteristic is identified using a custom UUID that is not part of the HomeKit specification. Because of this homekit_controller isn’t going to pick it up either.

What is the best approach to solving my problem? I want the homekit_controller to be responsible for discovering the device and then loading the custom component/platform (still don’t understand the difference) that would provide the entity for the Brid and the service to set it’s operating mode.