I considered this a continutation of the thread in the link below. I was going to reply to the thread but it's closed.

@PointOfNilReturn - @teeeeeegz - @pghinman - Did you guys ever got a solution to the original question?

https://www.hackingwithswift.com/forums/swiftui/how-to-handle-first-time-launch-experience-when-icloud-is-required/861

I have been thinking about it and to me the best way to pre-load data would be to check if the data exists before showing it in a view, if it does, check for duplicates and delete them, instead of checking NSUbiquitousKeyValueStore.

Please let me know if you guys find a better solution.

Here is a quick example of I'm thinking.

Present Data

struct DogsView: View {
    @StateObject var dogViewModel = DogViewModel()

    // Capture NOTIFICATION
    var didRemoteChange = NotificationCenter.default.publisher(for: .NSPersistentStoreRemoteChange).receive(on: RunLoop.main)

    var body: some View {

        NavigationView{
            VStack{
                List(dogViewModel.dogs, id: \.self, selection: $selectionServices) { dog in
                    // show dogs
                }
                .onAppear{
                    dogViewModel.loadDogs()
                }
                // Do something on NOTIFICATION
                .onReceive(self.didRemoteChange){ _ in
                    dogViewModel.loadDogs()
                }
                .refreshable{
                    dogViewModel.loadDogs()
                }
            }
        }
    }
}

Core Data transactions

class DogViewModel: ObservableObject{

    let manager: CoreDataManager

    @Published var dogs: [Dog] = []

    init(coreDataManager: CoreDataManager = .instance){
        self.manager = coreDataManager
        loadDogs()
    }

    // ADDS DELETES, UPDATES etc.

    func loadDogs(){
        let request = NSFetchRequest<Dog>(entityName: "Dog")

        do{
            dogs =  try manager.context.fetch(request)

            for dog in dogs{
                // delete duplicates and update dogs
            }

        }catch let error{
            print("Error fetching dogs. \(error.localizedDescription)")
        }
    }

    func save(){
        self.manager.save()
    }
}