OIDC _can_ have group memberships if the provider/client support it via claims.
LDAP is a pain because you have to expose/support a lot of knobs for integration (bind vs anonymous, secure vs unsecure, group format, root DNs, etc.). OIDC is (in theory) a lot simpler for the most part as the bare minimum is discovery URL, client ID, and client secret.
Kerberos, yes, but LDAP no.
What are your pain points integrating with LDAP? It is pretty simple.