I really don't see anything special about this keyboard. It's backlit and mechanical. Seems like it's been done a hundred times already.
For example, I'd think about reclaiming the top row, where the numbers live. On keyboards with a numpad, they're passengers. At the very least, invert the meaning of shift, so the default is to produce sigils.
I mean the next step IMO is to borrow inspiration from some computer game peripherals and allow buttons to be physically laid out in a different way.
You can get backlight keys in different colors through sellers that offer Ducky Keyboard brand backlight keys. You can find those in all sorts of colors and ISO/US formats, but nothing more than that unless you join some type of group buy through Geekhack.org or Deskthority.net where you can find all sorts of 'one-off' sets custom keycaps.