RetroPie/RetroPie-Setup ? reverse-engineered prompt

Build me a simple setup script for a RetroPie style retro gaming system on Raspberry Pi, and if possible also on a basic Ubuntu PC or supported Odroid and Vero4K setup.

I want it to guide someone through installing the needed packages, downloading the right emulator components, and setting up EmulationStation as the main menu for launching games. It should make it easy to get a working retro gaming box without having to do everything by hand, and on Raspberry Pi it would be great if it can support faster prebuilt installs when available, while still allowing source installs for other systems.

Make the experience friendly for someone who just wants to run one command, let it install what it needs, and end up with a usable retro console style setup. If you need to check current docs or package details online, go ahead and do that.