Earlier quoted context omitted.
It's fairly straightforward to install LineageOS on the Xiaomi Redmi Note 4 32GB [1], but they make you wait 72 hours before you can unlock the bootloader and I had to use a Windows virtual machine to be able to use the unlock software... 1. https://www.aliexpress.com/item/Global-version-Xiaomi-Redmi-...
I discarded anything Snapdragon, as incorporating the hostile baseband processor into the same chip as the trusted CPU is the wrong idea. This rules out an awful lot of the offerings, but at least there's Exynos (and Atom). I'd imagine the open-security-focused solution of the future will eventually push all that proprietary-algorithm-intensive hostile crap into something like a mifi.
there's already very few that have an unlockable bootloader