Hi 

Try code,

1. Load product barcode in POS.

    @api.model

    def _load_pos_data_fields(self, config_id):

        params = super()._load_pos_data_fields(config_id)

        params += ['custom_discount_reason']

        return params

2. Add the below js file:

patch(PosOrderline.prototype, {

    setup(vals) {

        var self = this;

        super.setup(...arguments);

    },

    get_barcode() {

        return this.barcode || '';

    },

    getDisplayData() {

        return {

            ...super.getDisplayData(),

            get_custom_discount_reason: this.get_custom_discount_reason(),

            discount: this.discount,

        };

    },

});

patch(Orderline, {

    props: {

        ...Orderline.props,

        line: {

            ...Orderline.props.line,

            shape: {

                ...Orderline.props.line.shape,

                get_custom_discount_reason: { type: String, optional: true }

            },

        },

    },

});

3. Inherit pos orderline for adding the barcode inside orderline.

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

<templates id="template" xml:space="preserve">

    <t t-name="Orderline" t-inherit="point_of_sale.Orderline" t-inherit-mode="extension">

        <xpath expr="//ul[hasclass('info-list')]" position="inside">

            <li t-if="line.get_barcode" id='barcode' class="text-info fw-bolder">

                <t t-esc="line.get_barcode" />

            </li>

        </xpath>

    </t>

</templates>

Hope it helps