Example value: "ExtendedVersion": "buildroot-2019.05.3-17-g522600d,skiboot-v6.5-242-ge19dddc5-p37cfc70,hostboot-820a099-pe030f7b,occ-3ab2921,linux-5.4.25-openpower1-p2339fe8,petitboot-v1.12,machine-xml-0f9b366-p7fb7a8d,hostboot-binaries-hw013120a.opmst,capp-ucode-p9-dd2-v4,sbe-0a77603,hcode-hw031620a.opmst"
I think it could be useful. Technically you could encode that all in the "Version" property along with the main version info (since it's just a string property), but that seems very ugly and doesn't provide much benefit to the client. Having a new property in SoftwareInventory (something like "ExtendedInfo" or "ExtendedVersion") would make sense to me since it can be used as a dumping ground of miscellaneous packages, but as I'm typing this, if clients really aren't expected to do anything with this data, maybe just leaving it as an OEM property in the SoftwareInventory resource is good enough. Still, I think it's worth thinking more about.
Another option could be to create a SoftwareInventory instance for each package, but I don't know if that will be particularly helpful to clients if you cannot update individual packages.