It should still be possible, just not with the existing SQL model and Swagger implementation. The driver probably supports the connection, but needs to be implemented in the PHP source code differently than the current SQL DB service implementation.
If you’re committed to contributing Sybase integration to the project, @Im_PJ, you will likely need to modify and/or add to SqlDbSvc.php and SqlDbSvc.swagger.php to add the calls that Sybase is expecting and handle the response that Sybase provides.