I am trying to build my own IAM service provider, but I have a little idea about IAMs. I am planning to use Axum for building this. If someone can suggest some resources for learning to build such a complex application it would be very helpful !
Kudos to you if this is a learning project, but please use well-established and well-vetted IAM solutions for your production services. I'd suggest familiarising yourself with Oauth2 and OpenID Connect and having a look at implementers and cloud providers. From there you could explore other authentication and authorization protocols like SAML, LDAP and Kerberos, but I'm not familiar with those. The Auth0 docs have proven quite helpful to me in the past. Other projects I'd have a look at are keycloak and ory.sh.