Thanks for your reply. I have seen that article before. While it's a creative idea, it's very customized and I could only imagine how long it would take to apply that style template or recreate that for someone pushing out lots of dashboards.
Any other thoughts?
For starters even I found it quite time consuming to create collapsible option. But overall this is the only way I have come across till now which I could manage in Tableau.
If you are going with this approach in a long term, you can save time by creating some template dashboard and reuse it to build others.
I have not used web app and Java Scripts to build navigation. But it does provide with multiple opportunities.