If anyone here is interested in creating more reliable mesh messaging, you might want to consider store&forward with efficient reconciliation as a primitive.

I helped create a library for reconciliation which might be useful: https://github.com/bitcoin-core/minisketch

One notion would be to divide time in to periods small enough to keep messages relevant, but big enough that all devices can be in sync well beyond that-- say an hour. Then constantly try to get every device it total sync over the last N periods. This kind of model can benefit from mobile devices... e.g. magnet a hub onto a trash collection cart and someone is magically ferrying messages from one side of the event to the other even if there are radio holes in the middle.

Use of efficient reconciliation keeps the traffic closer to O(devices + messages) rather than O(devices * messages) created by 'everyone repeats' messaging.

Unfortunately it hasn't really been an option open to the sort of devices that meshtastic runs on because they're extremely limited in memory.