When you mentioned Amber login, did you mean login via NIP-55 (Android Signer Application) rather than NIP-46 (Nostr Remote Signing)? I believe Amber implements both NIP-55 and NIP-46.

GitHub
nips/55.md at master · nostr-protocol/nips
Nostr Implementation Possibilities. Contribute to nostr-protocol/nips development by creating an account on GitHub.
GitHub
nips/46.md at master · nostr-protocol/nips
Nostr Implementation Possibilities. Contribute to nostr-protocol/nips development by creating an account on GitHub.