In 2018, I read James M. Tabor's Blind Descent: The Quest to Discover the Deepest Cave on Earth (pub. 2010), which particularly focused on Bill Stone's and ALexander Klimchouk's respective explorations. (Contrary to perhaps popular understanding, as evidenced by an answer I saw on Quora that asserted that the temperature got hotter and hotter the farther Klimchouk's team descended in "their" cave, Stone's and Klimchouk's teams started out high in the mountains and temperatures were freezing throughout the descents; furthermore, Stone's and Klimchouk's deepest descents still ended above sea level. [The Quora question had something to do with digging deep into the earth.])

Anyway, this was the first I'd read much about caving and, in browsing around the web, I discovered that Palm Pilots were(/are?) used by serious cavers for mapping caves. Auriga (https://auriga.top/) was the most frequently referenced Palm app I saw; its latest update was in December 2022. Obvious advantages as I understand them are: (1) long battery life coupled with replaceable AAA batteries; (2) a display that can be read in low light without battery-draining backlighting. Phone and wi-fi are useless underground. (I vaguely recall reading somewhere that ~80Khz radios for use in caves were being developed; equally vague memory: I believe initial prototypes were based around audio amplifiers that happened to reach up into that frequency. Okay, a 2018 Hackaday has links to more information, although not about what I [mis]remembered: https://hackaday.com/2018/07/11/ham-designed-gear-used-in-th...)

Also, sometime I saw an article about automotive performance afficianados using a Palm App to interact with their engines' onboard computers -- in the PalmOS Emulator (POSE) on Windows laptops. Obviously they liked the app and I imagine they had a considerable intellectual investment (e.g., historical experimental settings and performance results, etc.) that made them loathe to switch to more modern apps.

But yeah. I cleaned the battery crud out of my Palm M105 last month, put fresh batteries in, and the digitizer is shot. So, back to my phone ... :)