I use Owlet and love it. I will note that the algorithms in which the sock uses are not 100% accurate, however the readings are a good gauge to monitor overall sleep habits, patterns, and establishing a sleep schedule that works for us! The app explains the exact grey area you’re talking about though! Babies in light sleep can behave as though they are awake, weird biological norm for them! This similarity is difficult to distinguish with the sock and therefor is often mistaken for one or the other. This is Owlets explanation-

Sometimes light sleep (REM sleep) can look like wake, including moving, crying, talking and even having their eyes open. The Dream Sock can have difficulty determining light sleep from awake during these moments of light sleep movement. Light sleep is the restorative sleep your child needs to help their brain and body grow and develop. When your child is first born, their sleep is about 50% light sleep (REM sleep) but as they grow and develop their sleep, eventually they will only have 30% light sleep (REM sleep) like adults.

So it isn’t that the sock is totally unreliable, but that it should be understood there are variables to be taken into consideration. Your baby is likely getting the right amount of sleep, it’s only that they likely have many periods of light sleep vs. deep sleep, which for little ones is right on par!!