As of writing, the grading function in Lt is being improved. Therefore, what is said might be outdated when reading.
Here is a video walking through the grading workflow and options in Lt. Note that non-assessable questions, that is, those that weren’t set as Graded or Graded + Instant, can now be viewed in the grading interface. If students require an extension on the assessment, here is an article describing how to do so.
Grades can be exported as csv files, allowing you to import these into your grading system.
You can export grades from the following path:
Course Progress > Overflow menu (Three dots) > Export Grading
Note: you can only export grades for committed lessons.