last time i checked in on the project it mainly worked through 'seed' nodes which are analogus to relays because p2p was proving so unreliable. I'm not sure how much more decentralised it is in realit...
quote from https://radicle.xyz/guides/seeder :
"While a peer-to-peer network without seed nodes is feasible, it is impractical. This is because regular “user” nodes go online and offline all the time, so finding a user from which to download a certain piece of content can be challenging, or even impossible if all users with that content are offline. Therefore, a healthy peer-to-peer network necessitates at least some highly available nodes that participate in the network like regular peers, but seldom go offline. These are called seed nodes."
"While a peer-to-peer network without seed nodes is feasible, it is impractical. This is because regular “user” nodes go online and offline all the time, so finding a user from which to download a certain piece of content can be challenging, or even impossible if all users with that content are offline. Therefore, a healthy peer-to-peer network necessitates at least some highly available nodes that participate in the network like regular peers, but seldom go offline. These are called seed nodes."
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