I want to clear that P3A and P3P has different firmware, due to camera differences. The camera manage bird main controller firmware update! So as it is, you can't flash P3X fw (for P3P) on a P3S (for P3A), unless you do some (hard) hack. It's easier "probably" to hack P3A to flash P3P fw in case you install on P3A a 4K camera.
I would like to make some tests about that, but I only own P3P and not P3A... and there is a real big risk to brick all the stuff if the hack is incorrect ! I'm looking into fw to isolate the 4 different fw embedded, but it's not an easy task and really unsafe! And more, probably you get a warranty fly-away..