The problem is most embedded devices don't run Linux. They typically run a per-soc (or even per-board) fork of Linux, often dependant on fixed versions of binar

The problem is most embedded devices don't run Linux. They typically run a per-soc (or even per-board) fork of Linux, often dependant on fixed versions of binary blobs loaded from userspace. And that's assuming you can boot the damn thing without magic incantations and smearing lamb's blood on the correct pins of the SoC.