We – the modellers in the 3D_lgc network – have been uploading individual models to the 3D Warehouse, mostly for inclusion in Google Earth. That is all we need, unless someone comes up with a much larger set to upload. There is another means of uploading 3D models for use with 100 models or more at a time: “Cities in 3D”. guidance
By the way, Apple Maps include 3D city models: list.