gram_redirect.user.script.js

// ==UserScript==
// @name gram_redirect
// @namespace http://violentmonkey.net/
// @updateURL https://raw.githubusercontent.com/4ndr0666/4ndr0666_userscripts/main/4ndr0666_userscripts/gram_redirect.user.script.js
// @icon https://github.com/D0T7/Instagram-Redirect/raw/main/inst.png
// @version 0.1
// @description	Redirect Instagram
// @author    4ndr0666
// @run-at document-start
// @match *://instagram.com/*
// @match *://*.instagram.com/*

// ==/UserScript==

let redirectInstagram = () => {

  let url = "dumpor.com"; // change to some other ig viewer if this isn't working.
  let key = "/v"; // when you open a profile with the viewer it will show some other value  , eg dumpor/v/profile, set it to that,
  //and if it is not there , set it to "".

  if (window.location.pathname.indexOf("/p/") == 0) {
    window.stop();
    location.hostname = url;
  } else if (window.location.pathname == "/") {
    window.stop();
    location.hostname = url;
  } else if (window.location.pathname === "/accounts/login/") {
    window.stop();
    let oldQuery = window.location.search;
    let newQuery = oldQuery.replace("?next=/", "/");
    let newURL =
      window.location.protocol + "//" + url + key + newQuery +
      window.location.hash;
    window.location.replace(newURL);
  } else {
    window.stop();
    let oldUrlPath = window.location.pathname;
    let newURL =
      window.location.protocol + "//" + url + key + oldUrlPath + window.location.search + window.location.hash;
    window.location.replace(newURL);
  }
};

redirectInstagram();