The same degree of MainStage integration would also be possible with the SL MkIII, which is available in 49- and 61-key versions. The MIDI protocol is very different, but covers the same features as for the Launchkey Mk3, plus the additional capabilities of the hardware:
LCD display and button for each knob
LED for each fader
LED for each key (these could be interfaced via the update_layer Lua function)
I don‘t have an SL MkIII, so I won‘t be able to add support for it to this repository.
I set up the device in Logic Pro, then installed this device script and set it up in MainStage as well. After a few days of alternating between the two apps, eventually Logic Pro started picking up this device script too. It's not made for compatibility, so most things are broken. This happens even though the script is installed into ~/Music/Audio Music Apps/MainStage Devices, which seems like it should only be used by MainStage.