This doesn’t sound appealing to me. They’re surely storing this biometric data on a server somewhere, right? I use FaceID or my Apple Watch to pay with ApplePay all the time but my biometrics never leave my device.
I don’t follow Facebook all that closely (never used any of its services). Do they have other services that use (require?) face or fingerprint identification? Or is Facebook Pay a sly way for them to start harvesting this data?