Time Machine has methods for addings expaders. Via I2C pins or by sending/receiving Eurorack level signals to our 8-pin expander dealie. To be clear, these are not currently used by the firmware.
We made a passive expander for working with the 8-pins on the back of Time Machine. This will add the following types of signals for working with: 1x Gate in, 4 CV in (16-bit, bipolar 5V), 2 CV out (12-bit unipolar 5v).