Ask HN: Offline resources during internet outages?

I have a feeling that the risk for different infrastructure problems has increased here in Europe. Assuming internet outage for somewhat extended time, what would be good resources/tools to keep locally just in case? Some that I can think quickly from the top of my head might be:

- offline wikipedia

- offline stackoverflow

- youtube-dl

- libgen (are there tools to download e.g. only some genres?)