Authentication: Keycloak

So I am creating a concept for authentication within my software-platform. It should be possible for customers to use their own identity providers, like Okta, Azure AD, etc.

Anyway there should be a default identity provider, that will be delivered together with the platform. Authentication protocols will be SAML and oAuth/OIDC. I chose Keycloak for this.

My question is following: If a customer decides to use Azure AD as IdP, will Azure AD be used INSTEAD of Keycloak or additionally to keycloak (like chaining both services or something)?

What are the buzzwords I need to google for? 😀

Thanks!