I’ve never heard of honey powder. I’d imagine it’s similar to table sugar with slight fruity flavor. You could add it to any rub, but I’d be careful about it’s brining point. Simple sugar burns easily and leaves a bitter taste.
Speaking of strange things to add to any rub, I add citric powder to mine. It gives the meat a nice tangy flavor. If anyone has any strange ingredients that they add to their rub, please share.
Honey powder is dessicated honey (dehydrated and ground) once rehydrated it will burn like a mother. As does simple sugar as stated. Turbinado sugar, available at Latino markets and an increasing number of groceries, both ground and in cone form has a much higher burn point. Plus I think it brings a earthier flavor to the party. Try using ground turbinado in ice tea with lime for a twist.
If you can't find citric acid, try using unsweetend lemonade flavor KoolAid. (the small packages). A little bit goes a long way since when using as a drink flavoring it's sweetened by at least a cup of sugar The Limeade is also kind of interesting to play with.