You know, your feature is already implemented in renoise. No Fake! But it has to be programmed, or activated, first.
Not even that, I believe you just need to open MIDI mapping dialog (CMD/CTRL+M) and search for “Instrument”
The mapping “Current Instrument [Set]” will accept Notes/MIDI-CC messages which you can use to select any instrument.
If your controller is not outputting something useful then you can probably use xRules to convert it (I’ll be happy to make the script for you).