Beaglebone is even worse, with a PowerVR GPU and blobs to make the PRUs work correctly.

It's pretty difficult to find a device with completely open drivers, let alone open firmwares and memory initialization.

I do believe system76 laptops are almost completely open source other than the intel microcode.

That's because completely open drivers have no value even to tech. enthusiasts. If they did, vendors would offer them.

Yes you're right finding open source GPU drivers is hard. Rock Pi 4 with panfrost?