https://techcrunch.com/2023/06/21/apple-will-automatically-assign-an-apple-id-passkey-for-users-with-ios-17-and-macos-sonoma/

Apple will automatically assign a passkey to each user so they can log into Apple accounts on the web without needing any password. The company will allocate a passkey to Apple IDs starting with iOS 17, iPadOS 17, and macOS Sonoma.

The feature already works on iCloud.com and appleid.apple.com on the web for people running the latest developer beta on their devices.