odoo16/addons/stock_dropshipping/views/purchase_order_views.xml

<?xml version="1.0" encoding="utf-8"?>
<odoo>
    <record id="purchase_order_form_inherit_stock_dropshipping" model="ir.ui.view">
        <field name="name">purchase.order.form.inherit.stock.dropshipping</field>
        <field name="model">purchase.order</field>
        <field name="inherit_id" ref="purchase.purchase_order_form"/>
        <field name="arch" type="xml">
            <xpath expr="//div[hasclass('oe_button_box')]/button[@name='action_view_picking']" position="before">
                <button type="object"
                    name="action_view_dropship"
                    class="oe_stat_button"
                    icon="fa-truck"
                    attrs="{'invisible': [('dropship_picking_count', '=', 0)]}" groups="stock.group_stock_user">
                    <field name="dropship_picking_count" widget="statinfo" string="Dropship"/>
                </button>
            </xpath>
        </field>
    </record>
</odoo>