Is there a reason why we can't use a parameter?
Without using parameter you may not be able to get this at this point of time. I assume you want to show just the KPI's not broken by days, right? If latter you can use lookup.
I have a dashboard on Tableau Public that might be similar to what you are looking for
After much R&D I have created an idea which is currently being planned in future releases. Please upvote if you think it's useful.
parameter is static nature, how ever if new weeks will come , parameter will not update with new weeks dynamically, if we make parameter dynamic then issue is solved .