ovis-theme-color-script.user.js

// ==UserScript==
// @name         Expose `setThemeColor` window function to color toolbar of Chrome PWAs
// @namespace    http://tampermonkey.net/
// @version      0.1
// @description  A simple script to make it easier to set the appbar of Chrome apps via a small running after it.
// @author       @ovitrif
// @match        https://*/*
// @icon         none
// @grant        none
// ==/UserScript==

window.setThemeColor = (color) => {
    let name = 'theme-color';

    document.querySelector(`[name='${name}']`)?.remove()

    let meta = document.createElement('meta');
    meta.name = name;
    meta.content = color;

    document.head.appendChild(meta);
}