I installed a reader with a Wikipedia dump (without multimedia) on the original iPhone. At the time (at least in my region) WiFi was quite rare and it really did feel like the Hitchhiker's guide and incredibly powerful.

I only kept it for a few weeks though since it consumed almost all of the space. (And I imagine it was probably my language mutation, the english Wikipedia must have been too big already.)

You might look at Kiwix, and the data sources they've indexed: https://www.kiwix.org/en/

(Oddly, it's crashing at launch on my iPad right now)

I'm not trying to kill the fun here, but since this thing relies on a working internet connection, it would probably be pretty useless on a remote island

When SpaceX sends people to Mars they will want a local Wikipedia among many other things.

You can put a 43gb database on a $30 SD card and still have room for a bunch of movies.

You could host it locally easily enough!

Yes, but you could also host a normal Postgres db easily enough

This is entirely static, so I think it's easier.

Not entirely, the images are still loading from wikipedia.

Towel not included.

Sigh obligatory XKCD https://xkcd.com/548/

Hitchhikers Guide to Wikipedia? HHGTWP?