OS Releases: Debian Running on Android Devices Using VOLKSPC
The folks at VOLKSPC have released OS images in the past that can run Android on top of Debian.
They've now flipped that the other way, and released a Debian XFCE package that can run on pretty much any Android device, as long as necessary permissions are available (likely requires a rooted install of Android).
Check out the two videos below showing VOLKSPC's Debian running on an ODROID-C2 with Android, and also on an ODROID-N2 with Android. Sound from Debian even plays through the Android OS as you'll see in the videos.