Finally working!!!
So, for SonOff Dual R3 Wifi Model switch device the solution is found and working!
- Create an ambient in Ewe link app for your Sonoff switch device.
- Connect Ewe link app to Alexa
- Within Alexa app, create a routine based on the ambient created on first step.
- Connect Homey pro App to Alexa
- Within Homey Pro app using Alexa app you must add your Sonos speaker or echo speaker.
- Create a new workflow and on section, THEN you will have available trigger Alexa routine.
thanks, @Andy_Henderson !