as hinted in %8gOQchm... I recently toyed with this as well using #go-ssb
At first I got in over my head, trying to store keys as bytea
(so removing the base64 overhead) but this turned into a doozy when querying so I punted on it. Might be worthwile to reconsider at some point. Right now I just use postgres since I'm more use to it but if sqlite has decent json facilities as well I'd be game for that too if some one feels more inclined to colaborate on schemas and queries.
My main aim is rebooting ssb-pubmon and also having it for verifying your feed is updating to the mainet or forked for instance. It could might as well turn into an alternative viewer.scuttlebot.io implementation at this point.