So, it looks like nobody else has stepped up, so I'll give it a go.
I've made no sugar chocolate from callebaut liquor and allulose. It works well, actually. Unfortunately, you need a melanger to grind the allulose. Sugar does not dissolve in chocolate. At all. If you add the crystals to melted chocolate, you'll get chocolate with grains of allulose in it. The melanger grinds the sweetener until it's fine enough to not feel the grains when you eat it.
Unfortunately, you can't get around this by using a liquid sweetener, as those are almost always water-based, and adding anything with water will ruin the chocolate. This includes water-based flavorings.
Sorry if this was too basic, but it's a very common misperception. Let me know if you have any other questions, I'll help as best as I can.