We are trying to capture the external tools that are enabled (i.e. visible) across all our courses. The presence of external_tool_activation_id in the course_ui_navigation_item_fact table indicates this is the table that we would use, however it doesn't seem to include any external tools (i.e. all values are null for external_tool_activation_id).
We are finding the same thing. Our senior admins are chomping at the bit for numbers on the use of external tools, but we don't know how to give it to them without this column populated.
We received this response from Canvas Data Support last May and haven't heard any updates since:
I have found that there is a current issue our team is working on regarding these items being returned when pulling the course_ui_navigation_fact. I have attached this case to our tracker so our teams are more aware of the impact this is having on our users.
I recommend opening a ticket with Canvas support and/or emailing firstname.lastname@example.org to hopefully escalate the priority of the fix.