You must not be familiar with the luxury handbag market.
Correct, I don't touch luxury bags for the same reason I don't touch Connect-Tech and Leopard Imaging products. I pay for functionality and carrier boards are functionally just wrappers with some wires.
The alternative carrier boards all cost far too much, many more than the Nano itself which violates the first law of carrier boards [0]. Only the OEM carrier board is priced reasonably.
[0] A grocery bag should never cost more than the things that fit in it; a phone case should never cost more than its phone; a camera bag should never cost more than a camera; likewise, a carrier board should never cost more than what it carries.