I used the Barclaycard app on an X with no troubles (what I'd call "fake" FaceID signing in, IIRC) and I am using it again on my 7 with TouchID and zero problems. I can't say whether it supported the X screen resolution, but it definitely works with both TouchID and FaceID.
The Barclays Bank app supports Touch ID and now Face ID the Barclaycard app doesn’t.