Briefly skimmed over some stuff here: https://www.if-not-true-then-false.com/2015/fedora-nvidia-guide/comment-page-1/#comments
It’s not well organized and it’s generally a hot mess but I was able to get at least the gist of
1. Either need to sign the Nvidia blob driver or turn off UEFI secure boot. (I know you said you had UEFI).
2. Need to blacklist nouveau on kernel commandline (which I know remember doing myself way, way back in the day hence my earlier question). (OK obviously PopOS isn’t doing this but maybe they are not building nouveau in either?)
Not sure this helps at all but these two points do resonate with stuff I’ve either done or read about in the past. I do think there is even more to it than just this though.
Yeah—I’ve read those things before as well. With coreboot, though, I don’t think there is an option to turn off UEFI. At least, I haven’t found it yet.