Hi,

You can use the below code to bring the cashier's name in pos receipt,

In Js:-

odoo.define('pos_barcode.pos_qr', function (require) {
"use strict";
var { Order } = require('point_of_sale.models');
var Registries = require('point_of_sale.Registries');
var precio_unitario = 0
const PosCashierOrder = (Order) => class PosCashierOrder extends Order {
          export_for_printing() {
            var receipt = super.export_for_printing(...arguments);
            receipt.cashier= this.env.pos.get_cashier();
            return receipt;
    }
}
Registries.Model.extend(Order, PosCashierOrder);
});

In xml:-

<?xml version="1.0" encoding="UTF-8"?>
<templates id="template" xml:space="preserve">
    <t t-name="OrderReceipt" t-inherit="point_of_sale.OrderReceipt"
       t-inherit-mode="extension" owl="1">
        <xpath expr="//div[hasclass('after-footer')]" position="after">
            <div style="text-align: center;">
                  <p> <t t-out=receipt.cashier/></p>
            </div>
        </xpath>
    </t>
</templates>

Regards