I agree “origin” is not very clear, but it was meant to express exactly that, the origin of the goods being sold: https://wiki.openstreetmap.org/wiki/Key:origin
To describe the origin of goods, which are e.g. sold by a shop.
This key is especially helpful for shops which sell goods of foreign countries.
Since usage is still pretty low, a more accurate tag may have a chance.
I think origin could be a sub-key like goods:origin=* but “goods” is used differently already… We don’t seem to have an established tag for detailed things that are sold in a shop, maybe because this is opening a huge can of worms in regard to maintenance and verifyability. I really don’t want to try and update the inventory list of local convenience stores 
That said, “wares” is still free, so wares:origin=local is possible.
But I guess people could want even more detail than that. wares:local=yes|no|only could work.
