My wife recently turned vegan and has been making a lot of vegan treats ( if you can actually call a vegan treat a treat.)
Anyway,most recipes call for coconut oil because of its solid consistency at room temp.
Here is a link to a similar cookie with more than 1/2 the amount of sugar ( although its brown sugar) than your recipe above.
I dont think she has tried it so cant vouch for the recipe.
It also does call for less oats than your recipe, but even if you doubled the recipe, it still has less than 1/2 the sugar.
Vegan No-Bake Cookies Recipe - EatingWell
Another 'Treat' she makes are these date balls.
There no additional sweetners added to the recipe.
The dates provide the sweetness.
You would need a food processor.
These I have actually made and tasted and they truly are really good.
It is often used as a no bake pie crust recipe.