Make the release sign-in clients

Open Google Auth Platform → Clients (first do Get started with your app's real name, as in the development guide). Tap Create client. Android: Package name {{fodidePackage}}, SHA-1 certificate fingerprint {{fodideSha1}}, Create. Then again, iOS: Bundle ID {{fodideBundleId}}, Create.

These values are your released app's identity; Fodide gives them to you in the app's chat. The SHA-1 is the release signing key, different from the development one.