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].
You may be interested to note that NNCP integrated Yggdrasil support recently (though you can also run Yggdrasil at the OS level). Yggdrasil is an always-encrypted IPv6-based mesh, and is a perfect fit for something like ad-hoc wifi (since the nodes can discover a route to each other based even on RF paths).
Yggdrasil can also run as an overlay network atop standard Internet (IPv4 or IPv6), or both. It will opportunistically find peers on a local broadcast domain and find routes to other networks over the standard Internet if need be.
Feel free to drop me a note if you like; I had a very similar experience with SSB. NNCP, while it has a bit of a learning curve, Just Works. It processes thousands of packets for me every day (hourly ZFS snapshot backups for every filesystem I have), some of which are huge, and it Just Works.
Yeah, this use-case fascinates me as well. I've been noodling around with the idea of a 249-gram drone that flies SD cards between locations. BVLOS is still problematic in the US regulatory environment, but perhaps useful elsewhere. And I can always do demo flights indoors.
It would be ultra cool, IMHO, to fly SSB and NNCP traffic between "islands", whatever form those take. For bonus points, do it with pigeons, which have the advantage of operating in a GPS-denied environment.
I don't mind the full sync for SSB, I mind the lack of any progress indicator while it's doing so. But that seems like an easy UI tweak and maybe they've addressed it since I last played with it. What I haven't figured out is whether a brand-new user can sync from another existing user on the same island, or if they need a real internet connection for that first bit.
