Hello rlkoshak,
thanks for your answer!
Of course, I need to update to use the Feature (API with tokens → Home assistant). The Problem is, that the FS20 Binding is missing on the new Version. Not the other way around. I found on the Github Page OpenHab-Addons the compatibility Page (openHAB 1 addon compatibility overview with openHAB 3 · Issue #6179 · openhab/openhab-addons · GitHub)
In there is FS20 “Supported” with RFXCOM. This won’t help in my case. I need the 868Mhz running through the nanoCul.
Since Version 2 is working, I might add the Support to Home assistant via MQTT. That will need some time tho, since I am not completely sure, how to do that.