Bringing icons (in an emoji form) back to the MongoDB Atlas UI. Add this as your own UserScript in something like Tampermonkey and it'll give you emojis for the icons in the left-hand bar.

gimme-my-icons-plz.js

// ==UserScript==
// @name         Gimme My Icons Plz
// @namespace    http://tampermonkey.net/
// @version      0.1
// @description  Adding emojis in place of icons for the Atlas Project UI. This now handles the new redesign properly.
// @author       macintacos
// @match        https://cloud.mongodb.com/v2/*
// @exclude      https://cloud.mongodb.com/v2/admin*
// @require      http://code.jquery.com/jquery-3.4.1.min.js
// @grant        none
// ==/UserScript==
/* eslint-disable no-undef */
(function () {
  "use strict";

  let menuItems = [
    {
      menuTitle: "Clusters",
      newText: "🏘 Clusters",
    },
    {
      menuTitle: "Data Lake",
      newText: `🌊 Data Lake <span class="css-npw7us">BETA</span>`,
    },
    {
      menuTitle: "Deployment",
      newText: "🏚 Deployment",
    },
    {
      menuTitle: "Database Access",
      newText: "🔐 Database Access",
    },
    {
      menuTitle: "Network Access",
      newText: "📡 Network Access",
    },
    {
      menuTitle: "Advanced",
      newText: "🛠 Advanced",
    },
    {
      menuTitle: "Access Manager",
      newText: "🎟 Access Manager",
    },
    {
      menuTitle: "Continuous",
      newText: "💾 Cont. Backup",
    },
    {
      menuTitle: "Activity Feed",
      newText: "🧾 Activity Feed",
    },
    {
      menuTitle: "Alerts",
      newText: "🎉 Alerts",
    },
    {
      menuTitle: "Integrations",
      newText: "🧩 Integrations",
    },
    {
      menuTitle: "Settings",
      newText: "⚙️ Settings",
    },
    {
      menuTitle: "Charts",
      newText: "📊 Charts",
    },
    {
      menuTitle: "Stitch",
      newText: "🧵 Stitch",
    },
    {
      menuTitle: "Triggers",
      newText: "🔫 Triggers",
    },
    {
      menuTitle: "Docs",
      newText: "📚 Docs",
    },
    {
      menuTitle: "Support",
      newText: "🙅‍♂️ Support",
    },
  ];

  function detectElement(label) {
    let activeElement = `19zsrcl`;
    let otherElement = `1aen1ds`;

    let element = $(`.leafygreen-ui-${otherElement}:contains(${label})`).text()
    ? $(`.leafygreen-ui-${otherElement}:contains(${label})`)
    : $(`.leafygreen-ui-${activeElement}:contains(${label})`);

    if (!element.text()) {
        // These are for elements that are considered "inactive", and thus have a different leafygreen value
        let inactiveElement = `16rhx3s`;
        element = $(`.leafygreen-ui-${inactiveElement}:contains(${label})`);
    }

    return element;
  }

  function convertElement(element, textToReplaceWith) {
    element.html(`${textToReplaceWith}`);
  }

  function addIconsToSidebar() {
    let checkExist = setInterval(function () {
      // Using this to check if we've been loaded
      let buttons = [
        $('[data-testid="project-nav-invite"]'),
        $('[data-testid="project-nav-atlas"]'),
        $('[data-testid="project-nav-activity-feed"]'),
        $('[data-testid="project-nav-alerts"]')
      ]
      let leftNavLinks = $(".leafygreen-ui-bdnco");

      // Only do this next part if we have some navigation links to mess with
      if (buttons) {
        // First we do the buttons to make sure they have the event handlers
        for (let button of buttons) {
          button.click(addIconsToSidebar);
        }

        if (leftNavLinks.length) {
          // Now we do the sidebar
          let alertsSpanWidgetText = $(".alerts-widget").text();

          for (let item of menuItems) {
            let currentElement = detectElement(item.menuTitle);

            if (item.menuTitle === "Alerts") {
              // Special handling of alerts because it has a badge we need to keep track of
              convertElement(
                currentElement,
                `${item.newText} <span class="alerts-widget">${alertsSpanWidgetText}</span>`
              );
            } else {
              convertElement(currentElement, `${item.newText}`);
            }
          }

          // No need to check if the elements exist anymore at this point
          clearInterval(checkExist);
        }
      }
    }, 100); // check every 100ms
  }

  window.onload = addIconsToSidebar;
})();