Set ItemsSource of GridView not DataContext and then use another DataTemplate
<StackPanel>
<TextBlock Text="{Binding ProjectName}" Grid.Column="0" Style="{ThemeResource BaseTextBlockStyle}" Typography.Capitals="SmallCaps" Grid.Row="0" IsTextScaleFactorEnabled="False"/>
<GridView Grid.Row="1" ItemsSource="{Binding Releases}">
<GridView.ItemTemplate>
<DataTemplate>
<TextBlock Text="{Binding EnvironmentName}" />
<TextBlock Text="{Binding ReleaseVersion}" />
<TextBlock>hello</TextBlock>
<Border Background="#FF0CB90C" Height="110" Width="110" HorizontalAlignment="Left" Margin="0,0,10,0">
</Border>
</DataTemplate>
</GridView.ItemTemplate>
</GridView>
</StackPanel>