The Databricks SQL connector supports user OAuth since version 2.7.0. You just need to specify `auth_type="databricks-oauth"` and set oauth_client_id parameter to the Application ID of the AAD application with user impersonation permission on Databricks.  See code here: https://github.com/alexott/databricks-playground/blob/main/dbsql-with-aad-token/dbsql-with-aad-token...

It's also quite easy to add support for service principal auth using the custom credentials. Here is an example of how to do it: https://github.com/alexott/databricks-playground/blob/main/dbsql-with-aad-token/dbsql-with-aad-token...