There’s this one - a very different approach, but not in a totally separate universe when it comes to form-factor:
More in the realm of “specialized commercial” than “custom”, this keeb originated more from the depths of the Linux community than any sphere of keyboard enthusiasts - and how much one likes this keeb will depend a lot on their priorities.
There’s an old thread here about it that got a little spicy (a pretty rare thing 'round these parts), but from a distance I think it makes for an interesting ponder on different needs, use-cases, and priorities of keyboard buyers, designers, and manufacturers.