An error occurred while saving the commentAlex Nepple commented
You could certainly write an agent leveraging the WA APIs to update information between the directories.
For authentication, WA does not support custom external SSO options. As WA supports Google account log-ins, there is the option to use G Suite with Azure AD as your SSO provider. When they click to log-in using Google, they would enter there email address and then be redirected to Azure AD. This option is expensive as you would have to pay for a G Suite seat for each user.