I honestly thought I was the target audience, given I have bought mech keyboards, use them all day and want to buy more. So, in my book, I'm a real prospect but, yeah, maybe there's an even smaller niche.
I've never bought a mechanical keyboard but I'm a designer and the aesthetics + promise of a more tactile experience has me interested. I don't have a lot of comparison points or references beyond "MacBook butterfly keyboard gross, magic keyboard good".
The creator of the keyboard literally posted this to ask for feedback from HN users. I'm pretty sure in this instance HN users _are_ the target audience--or at least part of it. In any case, feedback is helpful at this stage (and is sought by OP).