follow-up - I installed and ran the plugin. Here’s the screenshot. I think it pretty much did what I had hoped. I need to tinker with the settings, but if you need an index, well, there it is!
Bottom left, you can see the index file. I opened it, then moused over some folders, following down to a file. I may change the index file prefix so that this view doesn’t show the index files first in each subfolder, but that may be what someone wants, so …
