Well, i’s been a long time since I used the pxfmini but I recently rebuilded it in my series of blogs on swarming
There are many thiings to consider when you build a linux based FC. first you need a RT Kernel that is better suited to near real time processing. I haen’t tried to build since Kernel release 5.x , but you can look at it:
Second, to make the binary , you have to get the correct cross-compiler suited with the correct broadcom chip (either Pi Zero or Pi 3 or 4). Then you can build using WAF command and specify the correct platform.
For testing, it is best to just copy the bin file to home directory and launch it manually using the correct mapping to the serial ports