To shoow Unit price in list view you have to inherit the list view "view_order_line_tree" of sale.order.line and add price_unit field in this view.

> <record
> id="view_sale_order_line_list_price_unit_inherit"
> model="ir.ui.view">
>            <field name="name">sale.order.line.form.inherit</field>
>            <field name="model">sale.order.line</field>
>            <field name="inherit_id" ref="sale.view_order_line_tree"/>
>            <field name="arch" type="xml">
>                 <field name="product_uom_qty"
> position="after">
>                     <field name="price_unit"/>
>                 </field>
>            </field>
>         </record>