Maybe we could use the old "bill of exchange". This can work even internationally, cause it is regulated under an international law. the underlying could be anything from wheat to cheese to gold, but no fiat money. (it could be traded by a blockchain, on the IPFS (interplanetary file system). That is decentralized and any pc can be a nod, even yours.
A Greek said, that during WW2 and the following civil war in Greece the ones who had olive oil and wine survived. True, I have both and soon a garden of half an acre. Even if not, we have wild plants here in Southern Peloponnese, one can collect.
This theory is most likely true, the Russians came up with it for over 70 years. The Deep Hot Biosphere, a book by Thomas Gold in 1999, is also pointing toward that.
We also know, that Greece has oil and gas (not just olive oil). It was not in the US interests, that they should exploit it...
video kills the piano player.