pos/pos_toledo_product/templates/templates.xml

<?xml version="1.0" encoding="utf-8"?>
<!--
    Copyright 2019 Coop IT Easy SCRLfs
    	    Robin Keunen <robin@coopiteasy.be>
    	    Vincent Van Rossem <vvrossem@gmail.com>
    License AGPL-3.0 or later (http://www.gnu.org/licenses/agpl.html).
-->

<odoo>
    <template id="assets_frontend" inherit_id="point_of_sale.assets">
        <xpath expr="." position="inside">
            <script type="text/javascript" src="/pos_toledo_product/static/src/js/devices.js"/>
            <script type="text/javascript" src="/pos_toledo_product/static/src/js/screens.js"/>
        </xpath>
    </template>
</odoo>