This would work if the sending node is directly connected, but if the architecture is "many Reticulum nodes, few Nostr nodes", then this is not currently usable.

So basically we can do link transport. Or if there is a way to see if someone is directly connected, we can switch to opportunistic broadcast.

Unfortunately this means that the relay sender needs to know topology and send each note to each relay on the way (which should send it over too). But if instant is not required, they might just sync over the air slowly once in a while, like old-times Fidonet.