Hmm. Having transferred the blog from Netlify to Render, the result is a resounding failure . If a deploy fails on Netlify, a manual retry usually works. Not so with Render.
If you are reading this then clearly the problem has been resolved, which probably means, at least in the short term that I’m using GitHub Pages.
This suggests there is a problem with my Hugo build, so if I want to persist with Hugo in the long term I probably need to rebuild it on the Pi.