This is really amazing stuff. Years ago, I was heavily interested in scuttlebutt [1]. I'm interested in grid down and "occasionally connected" communications. I particularly liked the island to island sailing analogy.
SSB has a few downsides - mainly that your client needs to download full logs. You can't just request the last 30 days. They call this out as well that your first sync could take over an hour and consume several gigs of data.
I'm just today learning about NNCP, but I've used FidoNet and UUCP in the past, so the concept is pretty familiar to me. In my mental model, I would be less interested in sneakernet than standalone wifi hotspots that one could connect to and exchange data, possibly combined with an AREDN style mesh[2].
[1]: https://staltz.com/an-off-grid-social-network.html [2]: https://arednmesh.readthedocs.io/en/latest/arednGettingStart...