The Android Supported Media Formats page mentions:
Note that any given mobile device may provide support for additional formats or file types not listed in the table.
Is there a way to obtain a complete list of all image formats that an Android device supports?
It's highly unlikely that device manufacturers would bother to support additional image formats so I wouldn't suggest spending much time looking into this further honestly. Also don't forget that even if one vendor supports a non-standard format, another probably won't.
If they did and they support compression of that format you could call Bitmap.CompressFormat.values() to get a list assuming they followed the Android pattern and you don't have an Android SDK released by the manufacturer to look at.