Show subChild categories

only getting deep in the code, but this should give the categories associated with the product

$sub_child = $product->get_categories();
foreach($sub_child as $a){
   echo $a;
}

if this gives the sub-child, child and parents, then must be built some kind of filter to show only the sub-child.

to the sub-districts I imagine something like:

$district = $product->get_attribute('pa_district');
$sub_district = pa_sub-district($district);
foreach($sub_district as $a){
   echo $a;
}