Instead of having something in the wall control unit replicate what Bond already can do, what are your options with wall control keypads within your current ecosystem?
You mention Z-Wave already – do you have a smart home controller that can listen for Z-Wave keypad presses and then issue a Bond API command?
Using something like this: Z-Wave Scene Controller
This is Insteon-based but the same thing would apply for Z-Wave:
Local API Control - Integrating with ISY994i