If the Internet went away, we’d have a little time before batteries were not viable even if replaceable, as distributing those batteries would get problematic.

Good thing portable solar panels & lead-acid batteries exist that can easily power a couple of laptops even if their internal batteries are cooked. Solar panels last for a very long time if cared for, and lead-acid batteries can be (somewhat) useful almost indefinitely if you replace the electrolyte.

No, we’re all gonna need to learn how to fight, and live without hospitals and drugs and probably electricity.

So it would be really handy to have instructions for maintaining or even building weaponry, medical/medicinal literature to find useful herbs or other remedies, and engineering literature/textbooks/software to help us rebuild the electrical grid and then the Internet.