Pseudo example for locale picker

locale.swift

import SwiftUI

// Can be in another file
struct DataManager {

    static let shared = DataManager()

    static let defaultRegionCode = "US"

    var countries: [Country] {
        get {
            let usa = Country(id: defaultRegionCode, name: Locale.current.localizedString(forRegionCode: defaultRegionCode) ?? defaultRegionCode)
            let others = Locale.isoRegionCodes
                .filter { $0 != defaultRegionCode}
                .map { Country(id: $0, name: Locale.current.localizedString(forRegionCode: $0) ?? $0) }
                .sorted(by: {$0.name < $1.name})
            return [usa] + others
        }
    }

    struct Country: Identifiable {
        var id: String
        var name: String
    }
}

struct ContentView: View {
    @State private var selectedCountry: String = DataManager.defaultRegionCode

    var body: some View {
        VStack(alignment: .leading) {
            HStack {
                Text("Selected code: ")
                Text("\(Locale.current.localizedString(forRegionCode: selectedCountry) ?? selectedCountry) (\(selectedCountry))")
                Spacer()
            }
            Picker("", selection: $selectedCountry) {
                ForEach(DataManager.shared.countries, id: \.id) { country in
                    Text(country.name).tag(country.id)
                }
            }
        }
        .fixedSize()
        .padding()
        .frame(width: 500, alignment: .leading)
    }
}