can we install px4 sable firmware in pixhawk 2.4.8 controller?
I did on mine, using QGroundControl. It is px4 v1.11.? FMU V2.?
Can’t remember it all and too lazy to look it up again. 
I’m going round and round with communication between
my Receiver and my PixHawk 2.4.8
Mine seems to have 2MB of Flash for the firmware,
so it probably doesn’t have one of those earlier version
processors in it, with a 1MB limitation on Flash size.
I did update the bootloader, which is designed to
load to 1MB or 2MB, after recognizing the processor’s hardware version.
v 1 and v Y are 1MB, v3 has 2MB
My understanding is that the px4 is standards-compliant firmware, expected to
be compatible with standards-compliant hardware. I am finding that discovering what is and isn’t can be tricky.
Good luck.