I will definitely take a look, then.
Well, since we are talking SAML or OIDC here - you don't really have a choice for the login/registration. The IdP provides the login and registration pages, not your application. You are free to build your own account management page, but you still have to ask Keycloak for a token.
I prefer to deal with account data and logic in a dedicated component that map with users stored in Keycloak. Even if you can associate custom attributes with user and groups, I don't think it's a good idea to do so (performance, separation of concerns, etc.).
For me Keycloak jobs is to handle authentication and authorization data and/or logic (authorization service is very well designed but a little bit complex), for simple use-case a role check in the application is enough.