Just some small info, not really a guide, just letting you know

I recently learned that there are Wikipedia Database Dumps and the whole english wikipedia including images is only around 110GB, thats as much as the newly released games lol. Kinda okay, for having one of the biggest sources of knowledge with you offline.

For this you can download a wikipedia dump in the ZIM format, its some special archive format, the recommended way of accessing it is via a software called Kiwix, which is actually open source. You can also download the wikipedia dump directly in kiwix, although tbh the interface looks kinda old :S But only the download section, once you open the archive, Wikipedia looks pretty much like usual.

Also you can use Kiwix as a Server, so e.g. you can put it on your home server, with some drive to it, have the server run and every device on your local network can access it.

And there are a lot of other Wiki Dumps available, like of the Arch Linux Wiki etc. So just experiment with it ;P