lefilament_move_view.xml

<?xml version="1.0" encoding="utf-8"?>
<odoo>
    <!-- Account Invoice Form - Trigger validation  -->
    <record model="ir.ui.view" id="lf_invoice_form">
        <field name="inherit_id" ref="account.view_move_form"/>
        <field name="name">account.invoice.form</field>
        <field name="model">account.move</field>
        <field name="arch" type="xml">
            <xpath expr="//button[@name='action_post']" position="attributes">
                <attribute name="confirm">Do you want to confirm this invoice ?</attribute>
            </xpath>
        </field>
    </record>
</odoo>