Typically, biometrics are only stored in your local device and the chip that holds that information is separate from all other storage and cannot be accessed by a network. The data the device holds also isn't an actual image, but a mathematical representation of certain features of your finger, face or eye, which is encrypted and impossible to recreate the source scan from. While it may be possible to hack a biometric system via code, they can't simply recreate your fingerprint from the data on your device.
None of these companies have access to your actual fingerprint, face or retinal scan. Your phone or computer verify your identity and then send an encrypted message to the authentication service with the key that was generated when setting up biometrics with it. Nothing is truly unhackable, but biometric login is way, way, way more secure than just a password string that can be brute forced or social engineered by any decent hacker.