No. Linux on PowerPC requires you to get down and dirty with the kernel 
Ubuntu 16.04 is Debian 9 so I would expect Ubuntu based on Debian 8 to work.
The latest Linux on PowerPC checks the architecture and then boots a 32 bit or 64 bit kernel based on PowerPC model. It is likely that check is failing on your hardware for some reason. The developers do not have every model of Apple hardware to test. If you can figure out what’s wrong and report the problem – it will get fixed.