Many of us went through a phase of trying various substances or blends of them for a "super substrate". Most of us soon learned that it works best to use either a single substrate material or a layer of a dirt-like material under a layer of fine gravel, preferably one with a good CEC. I have tried hydroton and found it either floats or is so near neutral buoyancy that it gets moved around all over the tank constantly. And, it offered no benefit unique to just hydroton. The Dyna Rok 2 is dolomite, which works ok as a substrate, but it does very slowly dissolve, raising the carbonate and general hardness of the water. Hyuga stone appears to be made from sea shells of some kind, and if it is, it is a calcium carbonate, which also slowly dissolves, raising the hardness of the water. Black Diamond is one I am now using, and it works fine as a top layer over dirt, or by itself.
I don't want to discourage you from experimenting with substrates. It can be fun to do, and there are enough materials that work well that you have a good chance to come up with a usable mixture.