Audio sidechain in a MIDI device

Venetian's icon

Hello,
the CV tools objects have examples for audio sidechain in both instrument and audio devices.
However, I find it's not possible to get audio input in a Midi-to-Midi device.
(I suspect that the sidechain looks which inputs are discoverable, and a MIDI only device does not have an audio callback?)

Can someone verify if this is the case?

thanks