Hello! I noticed that Noesis lacks CompositeCollection. The implementation of this improvement would allow adding static text or a button to the collection of elements without disturbing the order of the elements.
https://learn.microsoft.com/en-us/dotnet/api/system.windows.data.compositecollection?view=windowsdesktop-8.0

Usage example:

<ItemsControl>
    <ItemsControl.Resources>
        <CollectionViewSource x:Key="TagsCollection" Source="{BindingTags}"/>
    </ItemsControl.Resources>
    <ItemsControl.ItemsPanel>
        <ItemsPanelTemplate>
            <WrapPanel IsItemsHost="True" Orientation="Horizontal" />
        </ItemsPanelTemplate>
    </ItemsControl.ItemsPanel>
    <ItemsControl.ItemTemplate>
        <DataTemplate>
            <Border Margin="5">
                <TextBlock Source="{Binding TagText}" />
            </Border>
        </DataTemplate>
    </ItemsControl.ItemTemplate>
    <ItemsControl.ItemsSource>
        <CompositeCollection>
            <CollectionContainer Collection="{Binding Source={StaticResource TagCollection}}"/>
            <Border Margin="5">
                <Button Command="{Binding AddTag}">
                    <TextBlock Text="+"/>
                </Button>
            </Border>
        </CompositeCollection>
    </ItemsControl.ItemsSource>
</ItemsControl>

Below in the pictures I have given cases in which this innovation could be useful.