Oidc is easier to implement than SAML. Oauth2 is for authorization (vs authentication). Its used along with Oidc, but Oidc is the authentication piece (the SSO part)

I say Oidc is easier to implement because it is json based (jwt token) vs SAML which uses XML, which is very verbose and has stuff like namespaces and xsd’s which can make XML a pain to work with.

I’d suggest you stick to keycloak and set up Oidc. This is a good tutorial medium.com/…/keycloak-essentials-openid-connect-c…