After reading https://radicle.xyz/guides/protocol my first impression it's the same as how it works with Nostr with one key difference in the conceptual model. Nostr uses relays to distribute the data and Radicle is using a gossip model to distribute the data peer-to-peer (the bittorrent model).
They do explain the difference with a federated model. I miss the explainer compared to a relay model.
To me ATProto has not proven yet to be really distributed / decentralized.
In terms of "censorship resistant" you can also think of a 100% uptime of your code / work (your repository). Or always available for anyone with a internet connection.
In the context of a federated network (aka fediverse), that's often not the case (if a federated instance is unavailable, many assets will be missing leading to a unuseable application or service).
What crypto? Cryptocurrency or cryptography? This first one is optional to be used with the protocol. The second not (see NIP-01 https://nips.nostr.com/1).
Relays can federate. The point is that Nostr as a protocol is saying nothing about this and does not care either.
I'm running an indexer (a relay) which federates with other relay indexers. Similar how activitypub relays work. Any client can connect to indexer to help bootstrapping and find metadata around events. There are many ways to discover stuff from clients even without being connected to the same relay.