My understanding is that the screen wakes up to a slight nudge on the screen, though I’m not sure how well Face ID works at such an angle.

You can tap the turned off screen to wake up and it works from a surprisingly steep angle. (I just did this exact workflow)

I have an X right here, and it usually rests on my desk. It will unlock from a VERY oblique angle, way beyond what i expected it to be able to handle. The only failures i've gotten with the scanner were when a pillow was covering part of my face and i was in bed. Basically any position that i can reasonably read the display from that isn't a joke or a test will unlock the device if i'm glancing at it.

I have some complaints about the device, but this feature rocks as far as i'm concerned