"npub.cash uses Cashu-Address, a protocol built on Cashu and nostr. Cashu-Address allows a web server to provide Lightning addresses and mint ecash form the user's preferred Cashu mint. The user then redeems the ecash when they come back online."

its on the webpage

dont got time for nostr now, work calls. Enjoy the rabbit hole, tag me if you got more questions after your tried it out stu