How did you confirm this is a linux OS in the bird?
I installed LUCI on both my wifi extender and on the birds wifi unit, so I know those are linux for sure. Tbh, don't know what's running on the little Cortex M3 brain in the P2V+, but it's probably Linux too. And as for the flight controller itself, it's either an RTOS, or, more likely, also Linux.