Midihex from Gullsonix.
This comes in kit form. More info at their website.
I see they will be exhibiting at Syntheast in Norwich Feb 21 - 23, 2025.
They list their expansion plans :
Once the basic version has been established there are plans for further models with expanded keys and controls, and built-in sounds.
The source code is open source, which allows for customizing key layout. The potential exists to implement MPE.