How Screen Time API works with family authentication failed with error = 2

I've been trying to get something to work with the Screen Time API, but almost everything related to it is unimplemented.

I checked following links

Device Activity https://developer.apple.com/documentation/DeviceActivity

Managed Settings https://developer.apple.com/documentation/ManagedSettings

Family Control https://developer.apple.com/documentation/FamilyControls

Checked videos https://developer.apple.com/videos/play/wwdc2022/110336/

Problems I faced

• FamilyActivityPicker does not list installed apps on either of the guardian's or child's devices, it only lists the categories.
• There is no way to allow setting up of restrictions for individual kids, if we have many kids in family.

If anyone gone through the same problem please upvote or if anyone has a solution please share

Thanks