Sonos Volume control

[neocoma504]

Hi,

I recently bought a Sonos speaker and i was trying to do something i did previously with a bluetooth speaker : Increase volume slowly with an alarm set to play an Apple music playlist in shuffle mode!
I can configure the Sonos alarm to play the playlist i want in shuffle mode. All i need is to set up a slowly raising volume (I can use notification message as trigger). But Sonos is not a simple bluetooth speaker. So i cannot use a simple media volume raise function.
There is a Control API with setRelativeVolume function for Sonos systems, which would have been perfect! But it seems only cloud-based and usable by registered devs on Sonos, so i guess it's not for me...
The other possible solution is that there is an option on Sonos system to always use volume keys of the phone to control Sonos speaker volume. It works indeed even if not on the app. But i cannot find a way to control this volume from Automagic. The volume raise function in Automagic can only be applied to Sound Types : Alarm, DTMF, Music, System, Notification, Ring, Voice Call, Bluetooth SCO... But the Sonos volume slider is actually called "Sonos" and is showing a chromecast icon so it's neither of these... Also i tried to see if there would be an option to simulate the physical button press but i didn't find anything neither.
Does anyone have an idea if i could do this?

Thanks a lot!