I know that Canvas can save how many hours each instructor spent in each course:

I do not know what access you have in your Canvas.
In the past, a school I taught for would have the department chair added to every course as another instructor, so she could keep tabs on things. She would accumulate the information about how many hours the instructor spent in each course.
A word of caution: I was once called out for my claim that I spent all summer building a course, but Canvas showed that I had spent very little time in the course that semester. This was because I had copied the course from the template I spent all summer building into the shell for that semester. My boss did not check the template that I might have deleted before she asked. I did not even remember the template for several days; I was mystified as to why I had spent so little time in that course.