I've been using httrack (https://www.httrack.com) to download wikis to read on flights, which isn't perfect but better than I'd found previously. I'll try this out, I'd be delighted to have good results. Thanks for the post.
https://wiki.openzim.org/wiki/Build_your_ZIM_file
EDIT: https://get.kiwix.org/en/solutions/applications/kiwix-reader...
The executable file is mostly for people who don't have Kiwix installed yet, or just want to run the archive directly.