kite-bnf.user.js

// ==UserScript==
// @name         Kite rename instrument name
// @namespace    http://tampermonkey.net/
// @version      0.1
// @description  try to take over the world!
// @author       You
// @match        https://kite.zerodha.com/*
// @grant        none
// ==/UserScript==

(function () {

    console.log(document.readyState);

    window.addEventListener("load", (event) => {
        console.log("in load:", document.body.childNodes);
        let widgets = document.body.querySelectorAll(".instrument-widget > span > span");
        console.log(widgets);
        console.log(widgets[1].textContent);
        widgets[1].textContent = "BANKNIFTY";
    });

})();