I Moved to Linux and It’s Even Better Than I Expected
Dan Gillmor

You wrote:

I’m trying as many of these mobile options as possible, with the hope that I’ll find something good enough for daily use even if it’s not as convenient as the big players’ walled gardens.

Have you tried Jollas Sailfish operating system?

From Wikipedia:

Sailfish OS (also styled SailfishOS[4]) is a Linux-based general-purpose operating system, widely known as a mobile operating system combining the Linux kernel for a particular hardware platform use, the open source Mer core middleware, the proprietary UI contributed by Jolla, and other third party components some of which are free software, and others of which are proprietary.[1][2]