i think it would be worth potentially rebooting from the angle @average-vr-56795 mentioned above (as we discussed offline)... where you move the listing/manifest of artifacts->blob into the pants binary, or into BUILD files in the case of overrides, and then fetch them out of a store. i think the only bit that would still need design would be how you would key the platform specific bits: currently

name+version+binary_name

is a key, and then the rest of the mapping is defined by the store... would be more challenging to put the whole mapping in a pants option, or in a BUILD file, etc.