So when using avian carrier (microSD in backpack on carrier pigeon) or other sneaker net, a minimum of a full round trip is required to see updates. (Outgoing trip with pull requests, return trip with results.)

On SSB, you could publish a follow (bad for the evil govt scenario), and get regular updates without a pull request. Similarly on usenet. The tape cartridge would be preloaded with the current subscriptions when the carrier showed up. I wonder if there is a way to anonymously have standing pull requests?