And if phones used UEFI (or openfirmware or whatever), you could do just as well there (subject to driver support, but that's varied on PC, too). The absurd lack of standards in phone bootloaders and device trees is killing us.

You will probably be interested in Librem 5 or Pinephone.

Given that I own a Pinephone, you would guess correctly:D

I'm having trouble finding out whether this truly helps though; do either of those have a bootloader/firmware that provides device tree info to the booted OS, or are they still relying on the booted system to have its own device tree to describe the hardware?

EDIT: https://www.kernel.org/doc/html/latest/devicetree/usage-mode... implies that u-boot can probably feed a device tree file to Linux at boot time?

EDIT2: https://en.wikipedia.org/wiki/Device_tree says, "As an example, Das U-Boot and kexec can pass a device tree when launching a new operating system.", so yeah it looks like that would work! Sweet:)