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 ... :)