Solution was to send a heartbeat first to the pixhawk. I thougth this might be it, but needed sometime to track down the pymavlink command to do it. (the examples and doc pages i read before did not have this step).
my-land111_bbb.py @
https://drive.google.com/drive/folders/1eVXk6uqvKbY8qdOTGVSPfAdQDtaJMwVY