Gene, it isn’t simple to do. The additional devices are there for a reason. The battery in your aid is, I think, 1.4V or thereabout. The supporting devices and android phones and such are 5V. That difference allows transmission of stronger signals (wider bandwidth) to go to the low power device where receiving has lower power requirements. Putting android on a HA would make the hearing aids the size of a phone – may not quite but you get the idea.
The real problem is the control that the manufacturer exerts on what is there. It is all proprietary and limiting access to what can be accomplished. You are at their mercy.
Power is the true limiting factor. Your phone can use ISM/2.4G to send not only sound but picture to a smart TV. That’s because it can devote more power to the process which provides the bandwidth and speed that allows that. Bluetooth is a lower power device with greater efficiency and why they are using it for omnidirectional sound. It is much about compromises. At least that’s my take.