iCloud Keychain/Passwords has been syncing to Windows for years https://support.apple.com/en-gb/guide/icloud-windows/icw2bab...
Other providers like 1Password also offer cross platform passkey sync.
Other providers like 1Password also offer cross platform passkey sync.
A more native and higher quality Apple Passwords app for Windows wouldn't even really solve anyone's problems. I don't know the specifics on how the Windows Hello authentication layer works, but my assumption is: Apple can distribute this app, but this app couldn't just make its passkeys natively available to e.g. Chrome on Windows, without a browser extension which would effectively bypass the app anyway. And, Apple already has a Chrome browser extension.
What changed: Apple & Google want to enter deeper into customer connection and at the same time offer a more secure and convenient authentication for their customers.