Rummaging around (for an unrelated reason) I found my old Google Nexus 9 tablet (with keyboard). Coincidentally, it turns out that I could actually make good use of it in the very near future so I tried to get it going again. What else are weekends for? 
Well, after struggling with Google and its "play" store for several hours, I gave up fighting Google. Instead, I successfully restored the tablet by installing Lineage OS (version 16 aka Android v8). The Google apps did not install for some reason but who cares? I have F-droid, termux, muPDF, openssh, and Emacs! I'm all set.
In terms of hardware, it's actually quite a lovely system, with a nice screen and a very good bluetooth keyboard/case.