Obtain human ppg (ecg) data through mobile phone camera

We are developing a health product, and we need to obtain ppg or ecg data prepared by the human body through the mobile phone camera. I found some open source solutions. In order to improve efficiency, I want to find a friend who has research on ppg or ecg data to join me. , the detailed demonstration process is like this app:[Instant Heart Rate: HR Monitor](https://apps.apple.com/us/app/id409625068)