Arch doesn't, but as GroovyArcade is based on Arch Linux and I made the updates respect the Arch way, so it's just a matter of adding the repo then you'll have GM. This repo also has a patched SDL2 for KMS modeswitching + 15kHz kernel. So, if you JUST want GM, then add this repo as last, after the offical ones. Otherwise, add it as the first possible repo. I can provide further assistance for the pacman.conf edits