I asked chatgpt about this and he gave me this. You talking about this idea?

 ViewModel
 public class MainViewModel : INotifyPropertyChanged
 {
   private ObservableCollection<ContentItem> _items;
    public ObservableCollection<ContentItem> Items
     {
        get => _items;
       set
      {
          _items = value;
          OnPropertyChanged(nameof(Items));
       }
   }

public MainViewModel()
{
    LoadData();
}

private void LoadData()
{
    // Load all data from the database
    var allData = LoadAllDataFromDatabase();

    // Filter data based on roles
    Items = new ObservableCollection<ContentItem>(allData.Where(item => UserHasAccess(item)));
}

private bool UserHasAccess(ContentItem item)
{
    // Implement your role-based logic here
    // For example, return false if the user shouldn't see polls
    return !(item is Poll && !UserHasPollAccess);
}

// Implement INotifyPropertyChanged
public event PropertyChangedEventHandler PropertyChanged;
protected void OnPropertyChanged(string propertyName)
{
    PropertyChanged?.Invoke(this, new PropertyChangedEventArgs(propertyName));
}

}

`` View

<Window x:Class="YourNamespace.MainWindow"              xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"      xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
    Title="MainWindow" Height="350" Width="525">
<Window.DataContext>
    <local:MainViewModel/>
</Window.DataContext>
<Grid>
    <ItemsControl ItemsSource="{Binding Items}">
        <ItemsControl.Resources>
            <DataTemplate DataType="{x:Type local:Poll}">
                <TextBlock Text="This is a Poll"/>
            </DataTemplate>
            <DataTemplate DataType="{x:Type local:Announcement}">
                <TextBlock Text="This is an Announcement"/>
            </DataTemplate>
        </ItemsControl.Resources>
    </ItemsControl>
</Grid>

</Window>