There really are a lot of changes that make for a good install of retropie for Gpi. From boot/config.txt changes, to dtbo device tree overlay files (and renaming them to prevent an over-write), to quieting the boot text, to using a custom kernel with a boot logo, to a good splash screen video, to a good theme, to picking the right default emulators, to working around controller input issues with xboxdrv, to configuring proper es_system settings, to many other tweaks and changes. While it may never end up being an official "version" of retropie for Gpi, it really does become difficult to manage every single tweak and change that makes it better for Gpi. The guides might be the best bet for now, and maybe some day scripts can be created from the guides info that can just be run to make all the changes.