The Ultimate Hacking Keyboard [1] (link via Lobsters [2]) has a unique design, looking like a slightly-undersized normal keyboard but one that can split in half to allow for ergonomic positioning. It also split the spacebar in half, with the right side being the spacebar, and the leftside being another modifier key (personally, I would map the modifer key to backspace—it makes sense to me). I'm also glad to see them use a real mechanical switch with various models having differing “stiffness” factors (I really like the clicky keyboards). I do like the ability to mimic the mouse from the keyboard though.
The price, however, is a bit on the high side. But then again, I haven't spent more than $20 for a keyboard (even used, the IBM Model M [3] are solid enough to bludegon lusers with and yet, have a wonderful feel, if they are bit “clicky”).
[1] https://www.crowdsupply.com/ugl/ultimate-hacking-keyboard
[2] https://lobste.rs/s/xvfqcr/ultimate_hacking_keyboard