Hi,
the inputs and outputs are correctly enumerated in the main audio drivers (coreAudio, wasapi, wave, asio4all, directX, and the minifuse asio driver of course). The ability for the user to choose separate inputs lies to the application.
However there's software able to digitally route your audio sources from an application to another :
VoiceMeeter (Windows)
Jack (Windows / Mac)
iShowU Audio Capture (Mac only)
Soundflower (Mac only)
Black Hole (Mac only)
Rogue Amoeba Loopback (Mac only)