Google Pixel Face Unlock works with eyes shut..
It's been reported that having your eyes shut when unlocking the phone through face unlock can be a security risk. If someone else gets hold of the device and holds it in front of your face while your eyes are shut.
In comparison to the iPhone’s "FaceID" technology in the phone it detects if the user is alert when the phone is being unlocked.
Where as the Face Unlock feature on Android doesn't have that technology yet but Google has said in a statement that ’the face unlock meets the security requirements for a strong biometrics.’
Google has added to this saying that if people are concerned about the face unlock then they can activate a "lockdown" feature which turns off the face unlock feature.
There is an option coming to this biometric where it basically requires the user to open their eyes before the phone can unlock.
But it has been said that when the phone is launched on the 24th October 2019 it won't be on the pixel at first but after an update it may be added.
A cyber security expert said that if someone can unlock your phone while your asleep then it's a security concern.