<Grid>
            <ContentControl Content="{Binding CurrentItem}" />
        </Grid>

class ItemVM : public BaseComponent, public INotifyPropertyChanged
{
    ...
}

class BindingCollectionVM : public BaseComponent, public INotifyPropertyChanged
{
public:
    Ptr<ItemVM> m_item = MakePtr<ItemVM>(); // create ItemVM here

    void ButtonCmd() {
        m_item.Reset();  // Clear the item when a button is clicked
        _propertyChanged(this, NSS(CurrentItem));
    }

    NS_IMPLEMENT_INLINE_REFLECTION(BindingCollectionVM, BaseComponent)
    {
        ...
        NsProp("CurrentItem", &BindingCollectionVM::m_item );
    }
    

    void ButtonCmd() {
        m_item = MakePtr<ItemVM>();
        _propertyChanged(this, NSS(CurrentItem));
    }