The most significant missing feature is SASL authentication, which is also true for lualdap.
Azure Active Directory Domain Services (Azure AD DS) provides managed domain services such as domain join, group policy, LDAP, Kerberos/NTLM authentication that is fully compatible with Windows Server Active Directory.
Now it only supports bind and search (pending pull request).
The most significant missing feature is SASL authentication, which is also true for lualdap.
https://learn.microsoft.com/en-us/azure/active-directory/fundamentals/auth-ldap
So, if ADDS is configured to use Kerberos (GSSAPI), then we cannot even pass the authentication phase.