I was looking to build a custom frontend to manage all of my saved iCloud Keychain passwords.
This is not possible. Access to the iOS style keychain (called iCloud Keychain, when iCloud Keychain is enabled, otherwise called Local Items) is mediated by entitlements, and it’s not possible to get an entitlement that grants you access to all such items; you can only access items created by your team’s code.
Quinn “The Eskimo!”
Apple Developer Relations, Developer Technical Support, Core OS/Hardware
let myEmail = "eskimo" + "1" + "@apple.com"
Thanks for confirming. It was my suspicion.