Return ViewModel by View Name WPF MVVM

Question

I am new to WPF and the programming world in general and I need help. I am building a WPF MVVM application.

I want to create a method, which takes a View (or the name of a View) and returns its ViewModel. I need it to use an instance of the ViewModel in the MainViewModel (or ShellViewModel) without creating one with = new() everytime. I just want to put the name of the View as an argument and for it to return the ViewModel.

I was thinking of using ViewModelLocator from https://www.c-sharpcorner.com/article/datacontext-autowire-in-wpf/ and making it work for my case, but perhaps maybe there is a better way to do this.

Another idea is to add all the ViewModels in a class, e.g ViewModelCollector, and implement a GetViewModel method and call it in MainViewModel each time I need another ViewModel, but it's just an idea I'm not sure how to implement yet.

What is the best approach here?

What I have:

MainView.xaml:

<Grid>
    <ItemsControl ItemsSource="{Binding NavigationItems, UpdateSourceTrigger=PropertyChanged}">
        <ItemsControl.ItemTemplate>
            <DataTemplate>
                <RadioButton GroupName="Menu" IsChecked="{Binding IsActive, UpdateSourceTrigger=PropertyChanged}"
                            Command="{Binding DataContext.ShowPageCommand, RelativeSource={RelativeSource Mode=FindAncestor, AncestorType={x:Type UserControl}} }" 
                            CommandParameter="{Binding NavigationIndex}">
                    <RadioButton.Style>
                        //some style
                    </RadioButton.Style>
                    <RadioButton.Content>
                        <Grid  Margin="25,10">
                            <TextBlock Grid.Row="1" Text="{Binding Name}" />
                        </Grid>
                    </RadioButton.Content>
                </RadioButton>
            </DataTemplate>
        </ItemsControl.ItemTemplate>
    </ItemsControl>
</Grid>

MainView.xaml.cs:

public MainView()
{
      InitializeComponent();
      DataContext = new MainViewModel();
}

(MainViewModel should be injected here as far as I know but it currently doesn't work that way)

I have 2 other ViewModels, let's say FirstViewModel and SecondViewModel. Services are injected in the constructors of both ViewModels.

Every ViewModel (except MainViewModel) implements INavigation:

string Name { get; set; }
string Source { get; set; }
int NavigationIndex { get; set; }
bool IsActive { get; set; }

And there is a ConfigureView method in every constructor:

public FirstViewModel(SomeService service)
{
    this.service = service ?? throw new ArgumentNullException(nameof(service));

    //not important things

    ConfigureView();
}

private void ConfigureView()
{
    Name = "First";
    Source = "FirstView.xaml";
}

MainViewModel.cs:

public ObservableCollection<INavigation> NavigationItems { get; set; } //it is set in a different way, using INotifyPropertyChanged

public INavigation SelectedNavigation { get; set; } //it is set in a different way, using INotifyPropertyChanged

public ICommand ShowPageCommand { get; set; }

public MainViewModel()
{
    ShowPageCommand = new RelayCommand<int>(ShowPage);

    int index = 0;
    NavigationItems = new ObservableCollection<INavigation>();
    NavigationItems.Add(new FirstViewModel { NavigationIndex = index++, IsActive = true }); //error
    NavigationItems.Add(new SecondViewModel { NavigationIndex = index++ }); //error

    SelectedNavigation = NavigationItems[0];
}

private void ShowPage(int index)
{
    SelectedNavigation = NavigationItems[index];
}

The error is that there is no default constructor. How can I add the ViewModels to NavigationItems without creating an instance of them in MainViewModel?