When you have Amazon Alexa devices; you can make a workaround with the (beta) app of Amazon Alexa:
First I made a routine in the Alexa app which triggers my Robovac to start cleaning. After that I created a flow in Homey; when I push a smart button -> the Alexa routine will be triggered. Works pretty good, when l press the button the Robovac actually starts cleaning. In this way it should also be possible to make a flow based on presence I guess.
Only disadvantage is that I can only trigger the Robovac on or off via Alexa. It cannot be triggered to go back to the charging base. Anyhow, this is not a major problem since the Robovac goes back automatically when the battery is almost empty.