Thanks for sharing this. It sounds very interesting. E-cash can also be an option. It could be used for any service, IMO.
Discussion
the more I think about it the less I think so. ecash adds complexity which is just not necessary.
the simplest thing I can think of is SHA2(nsec + "lnzap") as your deterministic, anonymous token (or any random 32 bytes of data). then you can just use that token for all requests.
Well, this looks like a similar idea to L402 and https://github.com/cashubtc/xcashu. It will come to the differences and tradeoffs. Some stuff to think about ;)