Can anyone recommend a hardy device for viewing the content? As nutty as it sounds, in some post-apocalyptic world it would sure be nice to have. I'd keep it under the bed just in case..
I don't think that makes any sense. By that logic any currently working device should be assumed to last another $currentlifetime. My 20 year old car is not gonna last another 20 years. My 10 year old laptop won't last another 10. If my car somehow did last another 20 years, it would not then make sense to assume it would still be running in another 40.
Makes more sense to look at all objects of the same class. If 75% of laptops are dead in 10 years and 95% are dead in 15, and your laptop is 10 years old, you can infer that 5 out of 25 surviving laptops will make it another 5 years, or 20%. (These numbers completely made up, just an example.)
The problem with the "half life" rule is that it corrects for this in the dumbest possible way, not only providing an inaccurate estimate for most of the object's life, but even getting the first derivative wrong for most objects. Usually, lasting longer does not make the expected remaining years of service go up, but the rule implies it does!
Take people for example. At birth, a woman in the United States has a life expectancy of 81. If she makes it to 60, she can now expect to make it to ... 85. Not a big change! Every year she lived (even her first), her remaining life expectancy went down, not up. See this chart I made comparing the life expectancy of people versus a theoretical "half-lifer": https://0x0.st/otZ_.png
You might want a device like that to have offline maps as well, especially as those are more likely to be immediately useful. The easiest way to get there is the OsmAnd app - like Kiwix, it does a number of tricks to compress things, so it's quite feasible to have a complete offline road and topographic map of US in your pocket.
(Note that Google Play Store availability on the device is immaterial, since Kiwix and OsmAnd are also available as as downloadable .apk, and are also listed in F-Droid store.)