Hello dear Arturia community.
Hope that those requests make sense, I did not find any way to do this, so…
REQUEST 1.
Would be very nice that the KSP could send via a dedicated and specific MIDI channel the note which is pressed on the KSP keyboard.
The key pressed could be sent to another KSP (if request 2 is implemented, see below) or Beat Step Pro, or to the Arturia Modular VST, or any other external device to be able to chain the transposition key to several external sequencers in parallel. Indeed, it is not so nice that if I use the Modular VST I need a dedicated midi keyboard where the KSP could do the job 
So we earn a channel and can make benefit of the sequencer integrated in the Modular VST (or even several of course which makes things even more better).
Request 2.
Should be nice that the KSP when playing, could transpose the sequence via MIDI in.
This could allow to control the KSP from another KSP, so making it extensible. Note that the Beat Step Pro is working like this, which is nice as I can transpose from any MIDI keyboard, and it would be nice that the KSP and the BSP could work in a similar way. 