Hey there @fabiancpl, and welcome to the community! We have a Firebase auth integration, but it's for working with your Firebase auth data (i.e. using the admin SDK). In terms of using Firebase Auth to authenticate your Retool users, that should be doable via custom auth flows. Here's our docs on that:
https://docs.retool.com/docs/custom-api-authentication
You'd use the REST endpoints that Firebase auth offers in place of the internal placeholders we have here.
In terms of redirecting - generally, the way we handle these custom auth flows is to prompt the users of specific Retool apps to authenticate via a modal if the app queries a resource that requires it.