It was is all lazy lego stick together. Which I am not even sure is wrong entirely except for the lazy part.
I have looks a number of larger drone systems land, sea, and air. The state of the art is mostly off the self components, especially where it comes to scientific equipment and sensors because redesign of that stuff would blow the budget out and modification would risk function and invalidation of a tested tool.
So what you get is a drone with an Ethernet lan aboard along with the usual NAT router and some kinda of wan link, usually satellite but often mobile/cellular. Depending on the level of actual sophistication / development that router might sweep up and store the sensor data (or have partner server that does) and republish it or the router might just expose the individual components to some VPN.
When I first was asked to start looking at some of these 'platforms' I really expected more automotive-like engineering, thought I'd see CAN bus and body-module like patterns and you do but it is typically restricted to motor/servo controls, and navigational equipment that actually drive/fly/sail the things around.