I take back the "default web UI" being clunky. The IDP pages look great; the home pages do not, but that should be easily fixable with a simple index.html, which should be hosted on Solid.
I wonder if any Podserver out there can host a pod container (folder) as a website? i.e. just host the files in the folder, ignoring any content-empty ones? That would be a good use for Solid as well. Hell, give it a Gemini interface, host Gemtext on it!
...You know what, what if I did just that? What if I wrote a Gemini interface to Solid? Could I do that? I don't mean (just) an app, it would have to handle the login and maybe registration too, so you can do it all within Gemini itself. That would at least have to interface with the podserver with elevated permissions...