Highly interested in this, but I'm not really up to speed, and I wasn't able to figure out the protocol when I last tried. This is high on my list, will probably put it together in January — I'm bullish on the OAuth workflow. If you want to open an issue or PR on coracle, that would make me very happy.
Here it is, sending from Coracle signing with nip46 https://github.com/coracle-social/coracle/pull/205