I am looking to create app to authenticate users using facial recognition.

I checked Android provides Biometric prompt to authenticate the user but I am not sure if This API can be used for my use case. Also, if I can use this API, how many facial data can be stored on a phone, where would that data be stored ? 

If I can not achieve what I am looking for, through facial recognition, can this be done using fingerprint authentication. If yes, how many fingerprints can be stored on a device ?