We would love to offer every keyboard layout that exists, we are currently limited due to our size and the quantities that we make the keyboards in. Whilst it is technically possible to offer a custom layout, it would cost $165 extra to do and we don't feel this is competitive enough to offer.
That said, we will be offering additional layouts soon. As for which layouts, we plan to run a survey and simply go with the most requested :)
We recommend signing up to our newsletter as this is the first place any new options will be announced.