Not sure how relevant this is but we’ve been working on fully P2P communities / P2P bulletin boards for a few years. we even posted the idea here in 2021 Design idea to solve the scalability problem of a decentralized social media platform
in our design, most of the things are P2P, but not on any blockchain, peers join a libp2p gossipsub topic, and they use an arbitrary antispam challenge chosen by the community owner as the validation (antispam) function.
some mechanism to deposit funds somewhere and get credits to publish to the libp2p gossipsub topic is one of the most open and obvious way to do it, so it would be really useful for us and other similar projects like waku, farcaster, etc that use a similar antispam/DDOS strategy.
we are still seriously working on this project and have a few users and P2P communities running, but getting the antispam challenge right is the most difficult part at the moment. it’s difficult for users to easily onboard, yet also prevent people from flooding with spam.