OTOH if you want a quick favicon that renders consistently everywhere, Googles emoji set is available as SVGs (and fallback PNGs for Safari) under a permissive license.
Neat! I learned a few years back that you can use an emoji as a cursor using svg too, here's an example: https://codepen.io/lmmm/pen/LYpxzgV
I used this trick for a quick favicon on my site https://muxup.com/ - though unfortunately Google/Bing/DuckDuckGo doesn't like svg favicons and so it's not displayed in search results. I should really add a proper favicon...
Hm I wonder if it's possible to animate those svg favicons...
I have https://fav.rt.ht for you too! Let's you pick formats and customize layout/size.
Or if you'd like a PNG of a specific style: https://emojicdn.elk.sh/
See also: https://fav.farm/
Note that Safari still does not support SVG favicons.
This site has a nice one-click copy button for each "emojicon": https://emojicon.dev/