Hi,

Try to add the below at the end of the templates.xml, this will show internal reference in shop page for all products.

<template id="products_item_internal_reference" inherit_id="website_sale.products_item" active="True" name="Product Internal Reference">

<xpath expr="//*[hasclass('product_price')]" position="before">

<h6 class="o_wsale_products_item_title mb-1">

            <a class="text-primary text-decoration-none" itemprop="default_code" t-att-href="product_href"

t-att-content="product.default_code" t-field="product.default_code"/>

        </h6>

    </xpath>

</template>

Hope it helps