Normal map was baked from a Hi-Poly model onto triangulated Low-Poly. However the model in the Blend file is not triangulated. Model should preferably be triangulated before rendering/exporting to get the most out of the normal map.
The UnityPackage contains a Metallic map with Roughness map stored in its Alpha channel.
The Source Normal map has had its Green channel inverted and additionally the roughness map stored in its alpha channel. Including a perfect collision mesh for the model. The model is also of course scaled up to meet source engine scaling.