An idea in this vein I've been toying with is implementing a P2P IOU bartering protocol. I do something for you, you cryptographically sign me an IOU (which is a plaintext IOU note - no monetary amount required) which I can either call in later or trade to someone else who needs your services more for something I want from them. Messages sign adjacent messages (probably using Secure Scuttlebutt), so when someone comes back to you with the IOU, you can have a strong guarantee that it's the original note and not a copy even though you don't necessarily have visibility of all the participants it transited through.

Even in theory, it only works in some contexts, though, namely in exchanges between individuals. Because there's a strong reliance that neighbors in the path trust each other and leaves them responsible for settling exchanges to mutual satisfaction. All this proposal adds to direct barter is long-distance authenticity guarantees.