@ldix to do this one could list the body/ description of all assignments, quizzes, pages, discussion prompts. This could be done via Canvas Data or I believe also the API. For example, under Assignments API there is description field. Assignments - Canvas LMS REST API Documentation Perhaps run the API to GET the Assignment title and description. Once the HTML code is listed out in Excel format then it is possible to copy/ paste that text to a URL extractor such as : Extract URLs (We started to write a macro for this however found it easier to use an existing resource). Then export the file and sort/ remove duplicates in Excel. Voila! A list is created.
I speculate there are more creative ways to do this however the above is this end user's solution. ;o)