This app demonstrates a full end-to-end passkey implementation with a NodeJS server and Javascript front-end, using SimpleWebAuthn. The code is an express application, but re-jigged to work with Firebase.
This also works with the Android implementation at https://github.com/tdcolvin/PasskeyAuthDemoAndroid.
This code is also running here: auth.tomcolvin.co.uk.
Please open an issue if you hit any problems. And if you need help implementing passkeys in your own app then I'm available as a freelancer 😁. Contact me on LinkedIn or Bluesky.