PX4 on MRO X2.1-777

V1.11 now offers support for MRO X2.1-777 which flashes successfully to the fc (prebuild or from source)
But the boot loader doesn´t change from ChibiOS to NuttX/PX4.
After flashed to PX4 QGC doesn´t see it via USB anymore.
Only with Arduplane, which can be flashed back, QGC connects to the FC again. Is there an adapted bootloader available, that of the old X2.1 with F427 seems not to fit anymore.

On the search for a replacement for PixFalcon, which also fits into my projects in terms of weight and dimensions, I came across X2.1-777 in PX4 code, since I didn’t find anything else with at least 8 PWM outputs and under 10 grams.