purchase_product_matrix/report/purchase_quotation_templates.xml

<?xml version="1.0" encoding="utf-8"?>
<odoo>
    <template id="grid_report_purchaseorder_template_inherit" inherit_id="purchase.report_purchasequotation_document">
        <xpath expr="//table[hasclass('table')]" position="before">
            <t t-call="product_matrix.matrix">
                <t t-set="order" t-value="o"/>
            </t>
        </xpath>
    </template>
</odoo>