Last I knew, all SBC’s had processors with proprietary ISA’s, closed source microcode, and manufacturer-signed bootloaders. GPU’s were universally using binary blob drivers and the attempts to reverse engineer open source drivers were in very early days.
What progress has been made? Do I still need nearly 20-year-old computer to run Linux without closed source code running at some point in the boot sequence?
I don’t have any practical reason for this, frankly. Just makes me feel good and it’s interesting work.