High Level Conceptual Question - IoT, maker type projects

[MarkHaysHarris777]

It threw lots of error messages about casting Null to Int in the *.c file, so I assume even though the GPIO interface is consistent on the PI-2 connector, the internal addressing scheme for DMA and such is quite different on the Pine64.  Is there some reference I can use to port the RPi addresses used in that one source file to Allwinner A64 addresses? Or am I barking up the wrong tree there?

I think you're barking up the right tree... 

... and its all in the sources for RPi.GPIO-PineA64.  Back in the day of free software and before the open-source term came along, we would say, in true Jedi master style, "Use the force, read the source...   read the source Luke"

Yes the dts|dtb stuff on the PineA64 is completely different from the Raspberry PI !  It is after all, and completely different SoC manufactured by a completely different vendor; yes, an Arm design, but a completely different piece of hardware.   For instance, on the Raspberry PI there is no LCD back-light pwm  ( S-PWM PL10 ) on GPIO04 !  GPIO04 pin(7) on the PI bus, should be available for general use, but is not by default on the PineA64.