A grandchild component exposes a part named 'icon'. The middle component must re-expose it to the page so an outer ::part() can reach it. Using exportparts with renaming, which markup makes the OUTER page able to style it via my-parent::part(badge-icon)?
<!-- inside my-parent's shadow root -->
<my-child exportparts="..."></my-child>
<!-- my-child's shadow root exposes part="icon" -->