Ok the problem with Pioneer units is that they are resistance based and fixed resistance.
Lets say your volume up button has 5ohm resistance and lets say toyotas audio button have 7ohm resistance for volume up button.
In chinese units you can program any resistance to any key. So all buttons will work with chinese units. You press a key and whatever resistance it has it can be programmed.
Problem with pioneer units is that for volume up it has a fixed value lets say 2ohm so if your button doesnt send 2ohm them the unit will not turn the volume up it has its own set of values and you need to somehow change resistances of your button to what pioneer wants
For them to work you need a module that will change your resistance values to those of pioneer and its working in run time and changing values on each key press
You can get these from Amazon for like 50-60 dollars
Example Axxess ASWC-1
I did hear about a guy who has locally made one but he's in islamabad so if you are in another city good luck.
Or you can go to an amazing electrician and rip apart the button and remove the resistors from the circuit board of them and change resistors so that they always produce those resistances which pioneer units need