Easiest to set up IAM solution? (OIDC, OAuth2, SSO, etc.)

I've just looked at some tutorials for Keycloak and Authentik and there's definitely a very steep learning curve for these two solutions. I feel like I need something a lot simpler to be able to fully grasp the concept.

What is the easiest solution for beginners to implement Sigle-Sign-On for their selfhosted services?