a) Axa Remote 2.0

b) Arduino Uno R3 Shield KIT for HOME-LINBUS Devices Axa Remote 2.0 Window Opener
c)Geekcreit® D1 R2 V2.1.0 WiFi Uno Module gebaseerd ESP8266 Module voor Arduino Nodemcu Compatibel

Robbshop video on youtube, without technical details
I guess, communication is going to be like:
1) Domoticz -> MQTT gateway
2) MQTT gateway -> ESP8266 / Arduino UnoR3
3) ESP8266 / Arduino UnoR3 -> Linbus
Step 1 and 2 are described in the ESP8266 WiFi module Wiki; I will be starting with that. Step 3 is unclear for now.
If you have any tips: please join in