I had researched dumb phones recently only to learn that the two most important functions of a smartphone (for me) is the GPS and having a decent camera, and these things are either crippled or missing entirely from dumb phones. It's simply easier to dumb down your existing smartphone, especially if you have an Android phone. In my case, I have a 2017 Pixel 2 XL running LineageOS, with a text only home screen launche…
Literally tried to upgrade my Pixel 2 XL to Lineage and it failed repeatedly. Reddit says, no joke, it's the cable that's the problem. Sigh. Same computer didn't have issues flashing old Galaxy and Nexus phones. Bought a dumb phone but found it lacking for your exact reasons -- no GPS, crappy camera, and texting using the number pad was tedious as all hell. Gave up, got a Pixel 7, might think about flashing it.
Not surprising. My experience across a few different Android devices over the years is just about all USB-related functionality is a flaky mess, and that includes things like ADB and installing new ROMs. How it's flaky varies from device to device which makes it extra fun.