yes but what is the point of a consensus for a pubsub system?

the whole point is just best effort delivery of messages to interested parties, anything else is missing the point

a mechanism for creating E2EE DMs would be much more useful direction to query in - like, so, we have these schnorr pubkeys and schnorr signatures, how can we use this with taproot style tweaks and such to make it possible to have a stateless, metadata leakproof messaging protocol

now, you answer that one and you have actually solved a real problem