Hi Simon, Welcome to the community.
Within the obvious limits of the actual physical hardware (the buttons aren’t quite a hexagram) you can assign the buttons to any sound value you like, the only limitation is your technical skill. As I understand it, at this time you can modify it so that it sends any midi note you like from any key. I’m unsure of how it behaves when you use it’s built in synth. Even if you can’t change it in the web interface the entirety of the firmware is open source and an be modified with some mixture of technical know-how, patience and help from the kind people in this group.
Assuming that your needs aren’t just met by the web interface I put together a basic set of instructions for how to rebuild the firmware yourself. From there it’s a bit of fooling around.
Good luck,
Frank