Currently the docs for getAvailableBiometrics() say:

/// Returns a list of enrolled biometrics.

As noted in #187438 that's not accurate; it's possible for biometrics to be enrolled, but not available for the app to use (empirically this happens at least an iOS app doesn't have permissions, but there may be other cases as the iOS docs don't say when it can happen, we just know that "not enrolled" and "not available" are different states on iOS).

We should update the docs to clarify that it returns biometrics that are available for the app to use, and that this may not always include all enrolled biometrics. We can give the example of an iOS app with permissions denied to provide some context on what that can mean.