I wonder about the choice of MQTT for local access. It has the disadvantage of excluding anyone without a MQTT server.
Might it not be more useful to provide an API - or even a very simple http(s) interface? That way, anyone with access to the local network could query the CAD. An Android/iPhone App could be developed - maybe by a third party.
The ideal would of course be both facilities; but doubtless the CAD is short on program memory.
I'd be interested in others' views..