If you don't need the physical keys to change (and well, a keycap puller and maybe spare keys would fix that), you could get a remappable mechanical keyboard.
I've got an oldschool razer blackwidow - now sold as the blackwidow classic but many keyboards of this sort would have similar features.
- has proper switches.
- cause of this, you can just pull and move most keys around
- you can buy replacement keycaps, even as a set.
- backlight optional, there's models without it.
- You won't be a membrane key using plebian.
- You can disable, enable and remap keys to your heart's content
- You arn't spending several thousand dollars for reconfiguring a keyboard. My key puller cost three dollars.