My Environment
I am running OH 5.0.1 in Docker in Linux Ubuntu and it is working great.

Background
I have been using HomeKit for many years and had to rely on both openHAB and other tools, since OH does not support all accessory types. Now I would like to simplify my tooling landscape, which is why I am requesting this feature. Currently, I am using the Air Purifier for my ventilation device which exchanges air in our house.

Requirement and references to other implementation
I am current using the implementation in Homebridge mqttthing, and the link is here https://github.com/arachnetech/homebridge-mqttthing/blob/master/docs/Accessories.md#air-purifier

I am using these functionalities: Active, CurrentAirPurifierState, TargetAirPurifierState, RotationSpeed, FilterChangeIndication, FilterLifeLevel and ResetFilterIndication. Some are read only, which others are both read and write. I assume inspiration for the source code can be found in that repo.

Incentive
If someone can propose an alternative to Bountysource, I would like to offer a bounty for this functionality.