The polygon number was from within Blender and the 165M vertices was assuming each polygon is a triangle.
The double the Points//vertices from Zbrush to get triangles might not be 100% accurate (dog and drone examples as shown below show a small discrepancy)
Drone
175206 × 2 = 350.412/349.090
Dog
8013 × 2 = 16.026/15.968
but overall its a great rough estimation and rule of thumb which will for sure help!