Unfortunately there isn’t a way to export an entire course from D2L in a way that is cross Learning Management System (LMS) capable. This is because there isn’t a way to export D2L courses with a common LMS extension.
When you export your course from D2L its come in a IMSCP-compliant zip file. You can only import this file into other LMS’s that accept such file type.
As of right now the only other LMS, that we know of, that accepts D2L export files is Canvas.