vertical-cooperative/easy_my_coop_fr/views/layout_template.xml

<?xml version="1.0" encoding="utf-8"?>
<odoo>
    <data>
        <template id="layout_i18n_fr" inherit_id="theme_light.invoice_footer"
                  name="French Layout Customization">
            <xpath expr="//t[@t-if='company.company_registry']"
                   position="before">
                <t t-if="company.siret">
                    <span>Siret</span>
                    :
                    <span t-field="company.siret"/>
                </t>
            </xpath>
        </template>
    </data>
</odoo>