one of the "real" applications of Lidar, which is aerial photogrammetry, is to map terrain from the sky. It is very often done at night, as there is very little traffic. You should be fine with measuring objects in the dark with this iPad Lidar as far as I can tell.

About 3D printing - the iPad Lidar seems to have a _very_ low resolution, so for 3D printing you should wait for some next generations of micro-lidars.