There are a variety of ways that this can be achieved, but as you state not internally in Scaler at this time. The approach depends on what your DAW capabilities are. Most DAW’s recognise channel number in the MIDI stream, but Ableton Live (for example) does not. So even if Scaler could allow channel definition by rules, Live wouldn’t recognise this from a single port (there are some caveats to this, for FAPP it’s the case)
Of the several ways to achieve this (and setting aside Divisimate for now) a possible solution with Scaler as it is, is to process the rules externally to the DAW, then feed them back in.
One rational for using ports is that if your DAW was Live, these are recognised, whereas channels are not. See a trivial example at