RetroPie uses the Raspberry Pi OS Lite image - if that will support GPT for the root drive (boot + root), then RetroPie will have no issues with it.
Since the current RPI OS images are using MBR, you'd have to re-partition your disc and copy over the files to the new partitions if you want to use GPT.
@mitu oh ho, I know it's not supported. I tried it as my main configuration for a while and eventually it just would not start any games at all. I'm hoping that because it's on a secondary sd card it'll fix the issues i previously had.
If i had a choice, I would totally prefer to have it on top of raspbian but, whatever.
