You can customize the portal page of any folder (including subfolders) by adding web parts. See:
https://www.labkey.org/wiki/home/Documentation/page.view?name=addModule

If you would like to display the content of an R view, add the "Report" web part to a portal page. This web part is not yet documented.

I added an example to the portal page of the study demo temporarily -- see the end of the page:
https://www.labkey.org/project/home/Study/demo/begin.view?