No sure why you don't want to use the ^icon syntax, but can use it in the switch object key label.
Using only CSS is quite tricky, you have to use background with an url as explained in this link:
There was a bug when using the switch values as an array, and placing it in there. When I clicked on the switch with that icon, it wouldn't work properly. That's why I was wondering if there was another fairly simple way to add an icon in a menu or switch, but it does seem complex.