My best datapoints aren't ready yet, but here's something I spent a day and change on: https://github.com/jackjackbits/bitchat/compare/main...ynniv:bitchat:nostr-dual-signing
Discussion
A lot to dig through, but the technical description is nice on its own: https://github.com/ynniv/bitchat/blob/1f0852e8a12f8a3ffe11627e2d66ae1c24efe6de/BRIDGE_WHITEPAPER.md