Yes!
This is a similar but very different L3 implementation for privacy on lightning (plus you can do 🤯 things like offline tx): https://asats.io/
Being worked on by a Canadian too
Discussion
i think you can send all ecash offline or out of band, the receiver just can't verify the tokens are not already spent while offline.
btw there is already a solution figured out for issues like this:
you could create a programmable voucher, that has time locked refund conditions.
you can ask the mint to sign this voucher in exchange for redeemed fungible ecash. basically the recipient can give you something like a paynym or a nostr pub (public profile info), and you can lock in the funds while online.
then he can accept and verify this mint signed voucher when you meet offline that is say good for 2 days, after which you can claw it back if the deal doesn't work out. he can claim it at his leisure later that day.
it's not exactly intended for this fringe use case, but could work.
I thought this was using Cashu