Correct me if I'm wrong, but this seems to confuse hardware support (e.g. drivers) for "working out of the box" with a particular distro. I have a CM4. It worked out of the box with RPi OS, but needed some hacking to get working with Alpine. The important thing is that it was possible to pull some configs from RPi OS to set up wifi on Alpine. The drivers were all in both kernels, so I assume they were in upstream, but had no reason to check.

I think the point of GP is that some hardware on these SBCs has no open source drivers and you can't get them, which is way different.

Also, again maybe I don't understand something, but the RPi OS is not "bastardized" in any special way. The whole point of the Linux ecosystem is that you bastardize things. It's actually good that there is a distro customized for RPi and that it submits some changes upstream but not all, right? I think GP was saying that they didn't want to depend on some weird hacks the manufacturer did to get closed hardware to work, which again is different.