Hi @cwarren5,
I don't know of a simple single solution to this, and the question may actually be more complex than you realize at first... You'd probably need to define exactly what you mean by aren't using or updating the gradebook... Does that mean the grades area has to be visible to students? Does it mean all assignments have to be listed in the gradebook? Does it mean any weighing or other calculations need to be 100% accurate in Canvas? How often does a gradebook need to be counted (once a week, once a month, etc)... What you would need to do to find this data would depend on the answers to these (and possibly other) questions. In some cases, it may not even be possible to assess things until final grades are due (for example, to check accuracy of the grades in Canvas, as there is no way to know whether things are correct without having something else to compare against).
If you can let us know some of the answers to things above, someone may be able to suggest some approaches you could take to get the data.
-Chris