Via browser toolbar

via_toolbar.js

;(function(){
  const d=document;

  const css = d.createElement('style');
  css.innerText = `
    .ymb {
    position: fixed;
    bottom: 0;
    left: 0;
    right: 0;
    height: 28px;
    box-sizing: content-box;
    padding: 1px;
    background: rgba(0, 0, 0, 0.25);
    z-index: 99999;
    display: grid;
    gap: 16px;
    grid-template-columns: repeat(auto-fill, 28px);
    }

    .ymb button {
    background: rgba(0,0,0,0.65);
    border: none;
    border-radius: 8px;
    }
  `;
  d.head.appendChild(css);


  const bar = d.createElement('div');
  bar.classList.add('ymb');
  d.body.appendChild(bar);

  // Console button
  const vcb = d.createElement('button');
  vcb.innerText = '💻';
  vcb.onclick = function() {
    const s=d.createElement("script");
    s.onload=function(){ new window.VConsole() };
    s.setAttribute(
      "src",
      "https://unpkg.com/"
      + "vconsole@latest/dist/vconsole.min.js"
    );
    d.head.appendChild(s);
  }

  bar.appendChild(vcb);
})();