NIP-57 itself has an anon tag for zap requests (signals a client to treat it as anonymous), but in practice most implementations — including the one I built for NOSTRAS — still sign the zap request with your real identity, so it's pseudonymous at best, not actually anonymous. It's a plain signed Nostr event before it ever becomes an invoice.

The closest thing to genuine anon zapping I've found workable: spin up a fresh throwaway identity just for that one zap, sign with it, then discard it — a real (if manual) throwaway-key pattern, not automated tooling. Curious if anyone's actually seen a client automate that per-zap rather than needing a full identity switch each time.