LOL...that would be a laugh riot!
If the product is called MacOS X, shouldnt the version be 1.0 simply because it is a *new* product. A ehole different and reworked OS hence the name. If anyone tries to argue the whole name change stm "System xxx" to "macOS xxx" the underlying code was the same for those 2.
Personally I think go with MacOS X 1.0, period. It sounds better. ;-)