Want to show progress bar while moving to the previous page from the current page

For your UseCase , you just need to implement a Shared ViewModel between your fragments . I have not implemented your UseCase(Since I don't have your code ) . I have created my UseCase . It is a basic application using Navigation Component to navigate between fragments and fragment-ktx for easily creating a shared ViewModel .

First add the fragment - ktx dependency in your gradle file :

implementation "androidx.fragment:fragment-ktx:1.3.6"

Then first create a Shared View Model . Here I have just created a ViewModel with a function wherein it counts from 20 to 1 with a tiny delay and then updates the textView of the countDown it is current on . I have used MutableLiveData to communicate with fragments . You should have your download function here and you have to update your textView using MutableLiveData / KotlinFlow

class SharedViewModel : ViewModel() {

    private val _progress: MutableLiveData<Int> = MutableLiveData()
    val progress: LiveData<Int>
        get() = _progress

    suspend fun printFrom0to20() {
        viewModelScope.launch {

            for (i in 20 downTo 0) {
                _progress.postValue(i)
                delay(100)
            }
        }
    }

}

I have two fragments . In the first there is a button which navigates to the second Fragment and a textView wherein it shows the progress where it is current at though the function is called in the second fragment . In your scenario , your progress of how many images have been downloaded will be shown though not being on the fragment where it was started . Here is how the fragment look like . Here remember to use activitViewModel which create SharedViewModel

class FirstFragment : Fragment() {

    private val viewModel: SharedViewModel by activityViewModels()
    private lateinit var moveToSecondFragment: Button
    private lateinit var progressValue: TextView


    override fun onCreateView(
        inflater: LayoutInflater, container: ViewGroup?,
        savedInstanceState: Bundle?
    ): View? {
        // Inflate the layout for this fragment
        val view = inflater.inflate(R.layout.fragment_first, container, false)
        moveToSecondFragment = view.findViewById(R.id.moveToSecondFragment)
        progressValue = view.findViewById(R.id.currentProgress)
        return view
    }

    override fun onViewCreated(view: View, savedInstanceState: Bundle?) {
        super.onViewCreated(view, savedInstanceState)
        viewModel.progress.observe(viewLifecycleOwner, {
            progressValue.text = it.toString()
        })

        moveToSecondFragment.setOnClickListener {
            findNavController().navigate(R.id.action_firstFragment_to_secondFragment)
        }
    }

}

Now in the second Fragment , I have added a button which starts the countDown also a button to navigate to last fragment and also a textView which shows current progress .

class SecondFragment : Fragment() {

    private val viewModel: SharedViewModel by activityViewModels()

    private lateinit var startDownload : Button
    private lateinit var moveToFirstFragment : Button
    private lateinit var currentProgress : TextView

    override fun onCreateView(
        inflater: LayoutInflater, container: ViewGroup?,
        savedInstanceState: Bundle?
    ): View? {
        // Inflate the layout for this fragment
        val view =  inflater.inflate(R.layout.fragment_second, container, false)
        moveToFirstFragment = view.findViewById(R.id.moveToFirstFragment)
        startDownload = view.findViewById(R.id.startDownload)
        currentProgress = view.findViewById(R.id.currentProgress2)
        return  view
    }

    override fun onViewCreated(view: View, savedInstanceState: Bundle?) {
        super.onViewCreated(view, savedInstanceState)
        startDownload.setOnClickListener {
            lifecycleScope.launch {
                viewModel.printFrom0to20()
            }
        }

        moveToFirstFragment.setOnClickListener {
            findNavController().navigate(R.id.action_secondFragment_to_firstFragment)
        }

        viewModel.progress.observe(viewLifecycleOwner,{
            currentProgress.text = it.toString()
        })

    }


}

If you adopt to this code , you will see that the countdown can be seen at both the fragment . Using SharedViewModel concept you can create your own version as per your UseCase .

This is the demo of the application