Earlier quoted context omitted.
> I've been recommended to "just get a GPS" -- they're like $300, and I'm cheap :) Get a second-hand Android device for those tasks, install LineageOS and F-Droid/Aurora Droid, don't put in a SIM card and you're set for much less than $300. You'll be running free software - e.g. OsmAnd for mapping using off-line maps, no connectivity necessary - and you won't be feeding Google (et al) your data as you will using that…
... This is a _fascinating_ idea. I have a Pixel 4a right now, can I install this stuff on there and just switch to a dumb phone entirely for... phone purposes? It looks [0] like this shouldn't be too tough... [0] https://www.youtube.com/watch?v=PgNWaORMM9I
GrapheneOS is available for the 4a.