AFAIK [ “CurrentHumidity” ] is NOT supported at the moment. And you only see the group “Heizung” as a device in Alexa APP, that’s normal!
And you you need the maintag [ “Thermostat” ] AND ALL 3 childtags [ “CurrentTemperature” ], [ “TargetTemperature” ] and [ “homekit:HeatingCoolingMode” ]
see here: Official Alexa Smart Home Skill for openHAB 2
You have to tell Alexa the followings commands:
Alexa, set Thermostat to 22 degrees
Alexa, decrease Thermostat by 2 degrees
Alexa, increase Thermostat by 1 degrees
Alexa, decrease Thermostat
Alexa, what is Thermostat set to?
Alexa, what is Thermostat temperature?
in german:
Alexa stelle Heizung auf 22 Grad.
Alexa reduziere Heizung um 2 Grad
Alexa erhöhe Heizung um 1 Grad
Alexa reduziere Heizung
Alexa wie ist Heizung eingestellt? (I’m not sure about this!!)
Alexa wie ist Heizung Temperatur?