pos/pos_picking_load/views/view_sale_order.xml

<?xml version="1.0" encoding="utf-8"?>

<odoo>

    <record  id="view_sale_order_form" model="ir.ui.view">
        <field name="model">sale.order</field>
        <field name="inherit_id" ref="sale_stock.view_order_form_inherit_sale_stock"/>
        <field name="arch" type="xml">
            <field name="picking_policy" position="before">
                <field name="final_pos_order_id" attrs="{'invisible': [('final_pos_order_id', '=', False)]}"/>
            </field>
        </field>
    </record>

</odoo>