I will really consider buying one of these, because it looks really simple and nice with the wood panel and vandal switch.
However, I think you should offer mounting holes to flip the flex PSU, so that it takes in air from the bottom of the case, just like normal PSU:s do. If the intake is from within the case, the PSU is fed with warmer air, and becomes more noisy. This is especially important for these flex PSU:s that have a noisy smaller fan.
I sense that you want to make the case as compact as possible, but personally I would consider adding space for 2 92mm fans on top, as well. Even if the case is quite ventilated. And leave some space so that the fans are not pressed against the top, causing turbulence noise. The same goes for the CPU fan, which for compact cases is pressed directly against the side panel, causing turbulence noise. Same also for the GPU of course, but that is harder to fix. You just have to make the case larger. Also, some use very short motherboard standoffs to make the case even slimmer. I wouldn't use shorter than 5mm though, since it otherwise can cause problems.
That's a couple of things I learned from buying these small types of cases from taobao.
Also, I think there was talk about HDPlex in the comments. I read on reddit that HDPlex plans to phase out the current offerings, for new GaN combo units.