SwitUI, AppKit, services provider: how to ask user to select a choice in a list

I'd like to make a services provider in a SwiftUI application that request the user to select an option in a list.

Here is a sample working code (without asking option to the user). The App is based on a simple macOS SwiftUI application. Only the app.swift code is shown.

//

//  ServicesTestApp.swift

//  ServicesTest

//



import SwiftUI

import AppKit



@main

struct ServicesTestApp: App {

    @NSApplicationDelegateAdaptor(AppDelegate.self) var appDelegate



    var body: some Scene {

        WindowGroup {

            ContentView()

        }

    }

}



class AppDelegate: NSObject, NSApplicationDelegate {

    func applicationDidFinishLaunching(_ notification: Notification) {

        NSApp.servicesProvider = AppendSomethingServiceProvider()

    }

}



class AppendSomethingServiceProvider: NSObject {

    static let postfixes = ["one", "two", "three", "four"]

    var selectedPostfix = 0



    @objc func appendSomething(_ pasteboard: NSPasteboard, userData: String, error: NSErrorPointer) {

        guard let entry = pasteboard.string(forType: .string) else {

            return

        }

        // Ask for the string to append (one of AppendSomethingServiceProvider.postfixes strings).

        

        let postfix = AppendSomethingServiceProvider.postfixes.indices.contains(selectedPostfix) ? " \(AppendSomethingServiceProvider.postfixes[selectedPostfix])" : ""

        let output = entry + postfix

        pasteboard.clearContents()

        pasteboard.setString(output, forType: NSPasteboard.PasteboardType.string)

    }
}

How could I show a dialog here?