The Efforts to Extend ActivityPub

Device to device is also internet, also: nice p2p csam

Are you suggesting some sort of digital ham radio networking? That is honestly a good idea but it probably wouldn't be well suited for a platform like Lemmy and your device would have to be listening all the time which for internet devices is fine but can be challenging with two way radios. Then there's licensing costs since governments try to control radio spectrum usage, yes pirate radio stations are a thing but they have their own challenges. Also radio is at the mercy of the weather so that's yet another thing to keep in mind.

So with all those challenges despite the fact that it is an interesting idea it just doesn't seem feasible. What would be better would be coming up with more decentralized systems of trust to work on the internet, since one major point of failure is that our TLS security model is based on centralized entities, in addition to the domain registration systems.