I just wanted to share this little info for others here.
Our kids used to run to us parents all the time in order to choose the music or audio books for them in their room. So we figured out they needed their own Sonos controller. For obvious reasons, we didn't want to give them a full smartphone to do this. Here's what we did:
- find an outdated Android phone without a SIM card
- preferably one that is supported by Cyanogenmod or a similar alternative firmware
- install the opengapps nano package (Cyanogenmod explains it in their wiki) to get Google Play
- install the Sonos controller app via Google Play
- enable immersive mode for the Sonos app in Cyanogenmod's settings
- turn off the "double powerbutton tap starts camera" option in Cyanogenmod's settings
- install Mobilock Kiosk Lockdown app via Google Play
- in Mobilock, you can set the Sonos app to be started automatically
- once running, remove any other app except Mobilock and Sonos from the app switcher
We had a Nexus 4 lying around and the result is a small touchscreen controller that runs the Sonos app and nothing but the Sonos app. On reboot, Mobilock starts automatically and then hands over to the Sonos app. Immersive mode removes the Android UI buttons from the screen and gives you a fullscreen Sonos experience.
Mobilock is free and works well. It could have a nicer design and it isn't perfect, its kiosk mode isn't fully locked down and can be defeated by smart kids, e.g. if there are still other apps in the app switcher history.
But for our purposes, this solution works nicely.