I doubt nanite would be justifiable at that polygon density.
LWC is large world coordinates. I would only use it if you were planning a big open world game. It doesn’t really have any direct connection to Quad overdraw, it’s a way of storing the meshes coordinates to handle big worlds (64 bit floating points)
You could stream in the buildings internals if you are worried about overdraw. Basic wall overlap will be in part thrown away due to back-face culling.
For LWC you can look into the fornite article that tackles some of the problems between materials and large worlds