With reference to an old topic of mine, which is still actual, I’ve decided to jump the gun and develop my own binding for the Hydreon optical rain sensors.
I have a very preliminary version, which currently only supports the RG-9 device. The binding code is based on the Meteostick binding and adapted to my needs. No guarantee that the binding itself does not lock up after some time like I experience with the serial binding.
May be no one is waiting for this binding (I found that the RG-9 is far less popular than the RG-15 or RG-11) and people find it easier adding the Hydreon devices by means of ESPHome, but at least it has given me some coding experience 