getting Android/iOS certificates

I had developed an application with Expo a year ago. Now the requirements have changed and I had to include a lot of native code. I have made the decision to re-design the app and develop in natively on Android and iOS. To be able to submit it as an update for the Expo app, I need to get the certificates for Android and iOS with which the old app has been signed by Expo. Where can I find/get them?

Thank you!

You can use the following commands in expo-cli:

fetch:ios:certs [options] [project-dir]             Fetch this project's iOS certificates/keys and provisioning profile. Writes files to the PROJECT_DIR and prints passwords to stdout.
fetch:android:keystore [options] [project-dir]      Fetch this project's Android keystore. Writes keystore to PROJECT_DIR/PROJECT_NAME.jks and prints passwords to stdout.