Hi,
The schema type, along with all the rest of the schema is directly added in the view files of the product page.
So, you can create view overrides to change that, and more.
For example, if you edit product / show via the menu Display>Views, you can see this line:
<div itemscope itemtype="https://schema.org/Product" id="hikashop_product_<?php echo preg_replace('#[^a-z0-9]#i','_',@$this->element->product_code); ?>_page" class="hikashop_product_page <?php echo implode(' ',$classes); ?> hikashop_product_<?php echo $this->productlayout; ?>">
There, you can see the "itemtype" attribute.
Similarly, in product / show_microdata, you can find this code:
$obj->context = "https://schema.org/";
$obj->$type = $product_type;
which sets the product type for the JSON-LD