is it possible to add Long-term Statistics to the Rain sensors of Netatmo Public?
Sure, keep an eye on https://github.com/home-assistant/core/pull/56847.
Implemented in 2021.10.0
Edit: should be released with 2021.11.0
Are you sure? I still see that the sensor.py is updated the last time 2 month ago.
True, it was merged into dev but not released. Sorry for the confusion.