I think this is what this forum is for?
I don't really have any authority on this, but thought it would make sense if everyone used the same ports for this sort of functionality.
I would suggest using, say, port 10 (doesn't really matter) for all messages containing lua to execute, and putting said lua in the last part of the packet: (modem.broadcast(10, "username", "password", "gpu.set(0, 0, \"Hello World\")"))
Why is this useful? I can now have a single drone that works with many different programs with no real configuration. I can download programs via oppm, or paste them in from the internet, and they will always use the same port to access said functionality.