In writing this question I’ve answered it.
Note to my future self:
It should be fairly straightforward to run arcoreimg from the command line (I mean Terminal)
./arcoreimg eval-img --input_image_path=/Users/scull/Documents/Proj/Content/images/spoon.png
Only it seems that the arcoreimg executable isn’t named according to Android’s documentation. It’s ptdbtool_macos_lipobin and not arcoreimg as you’d expect.
mac38284:Mac chull$ ./ptdbtool_macos_lipobin eval-img --input_image_path=/Users/chull/Downloads/augmented-images-earth.jpg
100
mac38284:Mac chull$ ./ptdbtool_macos_lipobin eval-img --input_image_path=/Users/chull/Downloads/augmented-images-building.jpg
40
Also note that the image of Earth is 100 but the building is 40 and not zero as they report it to be.