(Fedora 40) "Nvidia kernel module missing, falling back to nouveau"

Unless you need that weird 6.0.8-xm1.0.fc38.x86_64 kernel, whatever that is, if you do get booted to the 6.8.8 kernel and get the nvidia working, I’d also suggest you dnf remove that old kernel from fc38 so it doesn’t accidentally get booted later.