As the title says:
When we fly or drive in Non-GPS navigation, how to load the map of Non-GPS map, such as indoor 2 dimention map?
You can write a plugin that creates polygons/points and adds them to the map.
Take a look at this: GitHub - EosBandi/OverlayControlPlugin: Proof of concept of user drawn controls on GMapOverlay
You need to change the coordinate system of your indoor map to the global coordinate system and then start the drone at the origin of the map.
If the drone has a compass, you will need to align the indoor map with north if it isnt already, transform the x y coordinates from meters to degrees lat and lon and then add a latitude/longitude offset (or it will appear at the poles).