I've tried to visualize polygons from OpenStreetMap in Unity. However, the main issue is that they get split a bit in Unity. I have tried to see if the centroids of these polygons match in QGIS and Unity and they do. Also, the size matches, which means the geometries are not scaled in Unity. I think the issue is related to the ArcGISMap, which probably scales a bit the whole coordinate system.
You can see on the image below the difference between Unity and QGIS. The size of objects is the same, and Centroids and ArcLocationComponent-s in QGIS and Unity are the same. However, there are gaps between objects in Unity, while in QGIS there are no gaps.