Discussion/topic based, as in like Reddit or HN? Not SSB, but NAB ( https://notabug.io/ https://notabug.io/ ) might be what you are looking for, also offline-fi

Discussion/topic based, as in like Reddit or HN? Not SSB, but NAB ( https://notabug.io/ https://notabug.io/ ) might be what you are looking for, also offline-first and P2P.