Thanks for the feedback. I'll edit it so the injection mold part is more prominent. Yeah I'm not aware of any concave keyboards that are injection molded that are hotdwappable.
It's TRS, which works with TRS and TRRS cords. I tried "mocking" a USB-C port and asking for feedback and got some people confused which port goes where, so just went with TRS in the end. It's not TRRS also because it doesn't with with TRS, whereas the opposite is true.
I used to sell dactyl minis like the one you pointed out. What I've found from customer feedback was that the thumb cluster needed to be improved. Specifically regarding 4 keys that make a square. Users reported they needed to move their thumbs in an uncomfortable way to avoid hitting the 2 keys that are closer, when reaching for the 2 keys that are further away.