For the moment, with Duniter V2S, there is no way to get a list of nodes from a node.
I have tried with RPC, no way.
I looked at libp2p then abandon the idea…
I am not the only one that need this feature 
On the telemetry ĞDev you can see the status of the network nodes, but I can’t find their endpoint information.
@elois said that it was possible to modify RPC to do that :
You can easily customize the RPC API: Custom RPCs - Substrate Recipes
So you can easily add what you need to get a list of known nodes, etc 
May be we could add it to the RPC requests or via an extrinsic…