In reply to Jeffrey Paul.

I wasn't looking for anything Gutenberg-specific, but I also didn't have that in the search terms either, so the fact that I didn't see anything likely means that there's nothing out there at the moment.

Since yours may be the first time I've seen "stripped down" and Gutenberg in the same sentence ;), I'll mention that I have been thinking/chatting with a few people about building a headless WordPress site with Gutenberg to support IndieAuth login that will allow access to the Gutenberg posting interface and have it act as a Micropub based client to allow using Gutenberg to post to any of the CMSes that support it. Of course that is far from simple or pared down in any sense of the word... I know that there was a Drupal project that was attempting to port Gutenberg, but this method may be much simpler and then have the benefit of working for a far larger class of CMSes.