Small treats with no icing sugar?

Do any of the shops stock that 'low calorie' stuff?  That would look and taste like sugar.

I work in a soup kitchen. One day, the only salt they had was Kosher salt, which wouldn't sift through salt shakers

A batch of rocky road cut into treat size bites.

Oat bars with a layer of sweet mincemeat sandwiched between the oat mix.

Rice Krispy treats.

Large dates stuffed with a little marzipan and a pecan [if you can get the ingredients]. 

You can make your own icing sugar by processing granulated sugar in a food processor, blender, or spice mill.  But you might enjoy Scottish shortbread, which uses fine sugar, which needs less processing. Look up Mary Berry's recipe. You can half-dip some of them in chocolate, or sprinkle some with coarse sugar.

There must be hundreds of bars and cookies you can make that don't require icing sugar. The only one I know that really needs it is Nanaimo bars, so I guess those are out. There are other ways to make icing that don't need icing sugar. Look up 'boiled icing'. I don't know what you consider exotic ingredients, and I don't know what you have in the house. I mean, telling us what you don't have isn't very useful for suggesting recipes. What you DO have is more to the point. All-purpose flour? Pastry flour? Eggs? White sugar? Brown sugar? Molasses? Honey? Corn syrup? Maple syrup? Butter? Margarine? Raisins, nuts, chocolate and in what form, spices, candied peel, peanut butter, marshmallows, rice krispies, cornflakes, lemons, oranges, cream cheese? All those things are possible ingredients. If I were you I would put 'square and bar recipes' in my search bar and look for a recipe that uses things I have.

I work in a soup kitchen. One day, the only salt they had was Kosher salt, which wouldn't sift through salt shakers.  A quick run through a Blender, problem solved. 

So is yours. 

Use granulated sugar and blend it in a spice blender, food processor etc until in makes a fine powder. Snickerdoodles don't need powdered sugar, just roll in cinnamon and granulated sugar.