This is a good idea but you have to be very careful with on chain privacy. I think that's why it doesn't exist yet. How do you generate the addresses from the pubkey?
Shakespeare on-chain wallet experiment: https://nostr-to-bitcoin.shakespeare.wtf/
Your Nostr identity is your Bitcoin wallet. You can send Bitcoin to any npub. No setup is required by either party. It "just works"
Discussion
vibing...
The input text box is hidden behind the keyboard so I can't see what I'm typing. Firefox on graphene.
Cashu routstr is perfect. I started vibing in 30 seconds.
It stops vibing when my phone goes to sleep so that severely limits usefulness.
BTW silent payment address derived from nsec is the best solution. You prolly need a hosted trusted index service to make mobile UX not terrible.