Normal Fitness tracker vs Fitbit

 Turn your normal fites tracker into fitbit!Fitbit is the industry leader- when it comes to personal sleep tracking and health monitoring. But have you recognized how it measures the REM sleep without directly measuring the user’s brain activity? During REM, our heart rate increases. But REM is part of deep sleep, where we stop our movements. So combining both, we can indirectly know when our body enters the REM phase.Activity trackers push raw data to phone via bluetooth. It is the phone companion app that acts upon the data to draw meaningful information. We cannot use fitbit app too since the app verifies, the device id.
Is there any way to mimic the fitbit device? or else we have to either modify the fitbit app or create or own algorithm.
The wearable device can detect our hand movement patterns (motion sensor) and the heart rate and send this data over to companion app.Companion app then calculates different sleep phases.