Implement Fido2 in Android and iOS using React Native

Question

I want to enable Fido2 authentication for passwordless login for my app. I read about Fido2 , but did not get proper information and the documentation is not clear, how to create the server and how it verify the data and all.

What I get till now is:

1. We need to have a server (it is our server or the FIDO server not clear yet)
2. If its our server, how to implement it and generate challenges
3. If we implement it on android and ios, the stick (fido devices) we attached to the device will the application auto detect it or we have to write separate logic for that
4. Any clean documentation on server implementation and react native implementation

I also looked in to the react native library for it but it works only for android, is there any that work with iOS too.

Also, anybody can put a light on the Fido2 authentication on android and ios and the server implementation or provide some links on the documentation for easy implementation that will be helpful.