Yes; i use this trick to display an upload progressbar (progress-donut?) using a bit of JavaScript: https://github.com/9001/copyparty/blob/c5988a04f/copyparty/w...

but note that browsers rate-limit you to approx. 1 update per sec

Extremely cursed, I love it

In principle, yes:

    data:text/html;charset=utf-8,<link rel="icon" href="
    data:image/svg+xml,<svg xmlns='http://www.w3.org/2000/svg' viewBox='0 0 100 100'>
    <g>
    <text x='0,0,100,0,200,0,300,0,400,0,500,0,600,0,700,0,800,0,900,0,1000,0,1100,0,1200,0,
             1300,0,1400,0,1500,0,1600,0,1700,0,1800,0,1900,0,2000,0,2100,0,2200,0,2300'
          y='.9em' font-size='90'></text>
    <animateTransform attributeName='transform'
                      values='0,0;-200,0;-400,0;-600,0;-800,0;-1000,0;
                              -1200,0;-1400,0;-1600,0;-1800,0;-2000,0;-2200,0'
                      calcMode='discrete' dur='1s' repeatCount='indefinite'/>
    </g>
    </svg>
    ">

However it doesn't seem to work on Chrome, even though it does handle the animated SVG correctly.