We are migrating to B2C. Current native solution uses libraries to do biometrics and calls APIs to authenticate with legacy IDP. We want to use web view for B2C on the native implementation and I read that it is not possible to incorporate biometrics into the web view and B2C flows out of the box.
How about if we continue to use the native libraries to pass the biometrics and then pass a signed input claim to a custom B2C sign in policy which can skip username/password screen and continue the journey to sign in the user? Is it a feasible solution?
I have not found any similar use cases and references other than the old WingtipGamesB2C sample repo for invitation flow This sample uses a similar idea for create account passing in a user identifier to the policy as an input claim.
The technical name for this is "id_token_hint" or "magic link".
I posted about this a while back. The post has several links to B2C samples:
I also wrote a post about hosting the id_token_hint well-known endpoint in Azure AD B2C, which saves having a separate web site.