flectra/addons/sale_expense/views/product_view.xml

<?xml version="1.0" encoding="utf-8"?>
<flectra>
    <record model="ir.ui.view" id="product_template_form_view_expense_policy">
        <field name="name">product.template.expense.policy</field>
        <field name="model">product.template</field>
        <field name="inherit_id" ref="sale.product_template_form_view_invoice_policy"/>
        <field name="arch" type="xml">
            <field name="service_type" position="after">
                <field name="expense_policy" widget="radio"
                       attrs="{'invisible': [('can_be_expensed','=',False)]}"/>
            </field>
        </field>
    </record>

    <record id="product_product_view_form_inherit_sale_expense" model="ir.ui.view">
        <field name="name">product.template.expense</field>
        <field name="model">product.product</field>
        <field name="inherit_id" ref="hr_expense.product_product_expense_form_view"/>
        <field name="arch" type="xml">
            <xpath expr="//group[@name='product_details']" position="inside">
                <group string="Invoicing">
                    <field name="invoice_policy"/>
                    <field name="expense_policy"/>
                </group>
            </xpath>
        </field>
    </record>
</flectra>