You can target individual icons/items inside a super tile you will need to know the icons order number. You will change the ? to the number of your icon is based on its order in the super tile.
.--theme-style-YOURSTYLENAME.super-tile .item:nth-child(?) {
-webkit-filter: drop-shadow(0 0 3px #ff0)drop-shadow(0 0 10px #ff0);
filter: drop-shadow(0 0 3px yellow)drop-shadow(0 0 10px yellow);}
I agree this would be nice if it was native, but I personally believe there are features that are more important to be developed first.