Hi @mark,
I’m not certain what you mean by this - BlueOS is the software that runs on the onboard computer, and enables communication between the topside computer and the autopilot board, and ArduSub is the firmware that runs on the autopilot board - their build procedures are unrelated.
If you’re asking about building ArduSub on e.g. the Navigator vs a Pixhawk, that’s handled by the configuration options provided to waf.
If you’re asking about installing BlueOS onto something other than a Raspberry Pi 3B/3B+/4B then you’ll want to look into the install directory.
Hope that helps! 