An easier way to think about is to design the air dispersing ports to cross the bulk of the water flow. Here are 2 external mixing nozzles
This one requires the water meet at the vertex of the air ports.
This one seems like it would fit the existing aquamist nozzle, but it would require some thought into the angle of the air ports.
I haven't tested it further, but I think you could make a modular system whereby your standing nozzle screws into an external mixing base. It would likely be the second type.