> Now maybe the O6 also happens to only use hardware which works with upstream kernels, I don't know.

I think so because I looked in up when it was released and people were able to boot standard images ("All UEFI based ARM images with Mainline Kernel 6.6 and above" [0]). Their specific Fedora and Debian images reflect the progress in better support in the CPU, GPU, etc.

Looking back I should have bought many of those just for the 64Gb of RAM...

- [0] https://sbcwiki.com/docs/soc-manufacturers/cix/cd8180-p1/boa...