How to add Apple Game Center leaderboards to an Expo app

I shipped my indie game Chromatch with Apple Game Center leaderboards earlier this week. My first submit got approved with the binary alone and my 6 leaderboards stayed "In Preparation" with no warning from Apple. It took a re-submit to find all the pieces that aren't obvious from the docs. Here's what ended up working, code included. The native module Expo doesn't ship any game center package, so you have to write a small local module with npx create-expo-module@latest --local . Here's the Swif