As of now, none of this is “supported”. There will need to be significant infrastructure work done in darktable itself to enable clean integration of this module (with “note” key mapping support as well).
Separately, I cannot find any information on what protocol loupedeck uses; it does not seem to be a midi controller and requires an sdk to develop a plugin (which so far is only available for Loupedeck CT). So it looks very unlikely that I would be able to do anything with it.
If I’m wrong and it actually does send MIDI codes, you should be able to define your own mappings/layout. In which case I’d love to hear your results.