Comment by audiodude

Volunteer for Kiwix here (https://kiwix.org), we do a lot of offline Wikipedia stuff. I've personally worked on MWOffliner (https://github.com/openzim/mwoffliner) which scrapes MediaWikis, primarily Wikipedia.

We have apps for basically every platform. Our PWA even supports IE 11!

You can use the WP1 tool which I'm the primary maintainer of (https://wp1.openzim.org/#/selections/user) to create "selections" which let you have your own custom version of Wikipedia, using categories that you define, WikiProjects, or even custom SPARQL queries.