It's fine until you realize the i915 patch was based on work from 2014 and updated in 2018. And that update is 100% untested by the person who made the updated patch because they don't have a iGPU.

That wasn't a typo. Go read the patch notes.

I also have a iGPU that uses i915 and have never had this VGA issue with QEMU/VFIO, making me question if the patch is needed at all.

This is just one of the many reasons to compile your own kernel.

The difference is instead of running yay or makepkg you use make. That's it. Arch isn't intended to be a beginner friendly distro. You didn't say you were running Manjaro or Antergos, but Arch.

The Arch install process is more or less the same install process for Gentoo, minus emerge. Especially if you follow a quick install guide.

Anyway, at this point I can't convince you to not use linux-vfio. Instead, I would like to challenge you to download the package, remove patches you don't need, modify the .config file to suit your system so it's not a all-in-one solution and then run makepkg on it.