its an interesting journey they have been on. v1 used IPFS. v2 used Secure Scuttlebut. Now they are on version 3 which uses a custom gossip model.

2 years ago the Rad token was prominent and Etherium integration was under active development. For example in this video someone from Radicle tries to put a ownership attestation of a git repository onto the ETH chain but gas fees were $700 so they didn't have enough in their wallet.

https://youtu.be/urYFgt6HOTQ?t=2031

There now appears to be no mention of etherium and Radicle "doesn't use nor depend on any blockchain or cryptocurrency"