Did you get your 1st prototype yet?
Did you include mounting support for a res/pump?
I don't think it's particularly worthwhile funneling down to one particular pump. First off, not everyone may have access to that particular parts, and considering how open-ended and flexible this case is, there's too many potential hardware combinations/mounting locations to consider. For example, offering a mount between the PSU and motherboard will funnel people towards ITX boards, while being of no use for people who use ATX boards. Or, having the pump mount on the lower side of the case may restrict GPU length and/or get in the way of 120mm rad mounting.
I think it's better to let the customer figure out what spacing is available for their own very specific combination of hardware, and drill holes exactly where they want the mounts to be. Offering one or two prescribed mounts for one specific pump may potentially limit the flexibility for people who have no plans to use that specific mount or may limit space/clearance for their own choice of hardware.
My only genuine concern is for people who are using 3+ of the PCIE lanes on an atx board and looking for a smaller case, such as myself. Using riser cables has always been very off-putting for me
Which is a perfectly legitimate compromise, honestly. The main draw for this case is it's very small footprint, so I can keep it under my desk by my feet. Assuming the case material is steel, what are the overall dimensions for the hole cutout area? I'm planning to add some dust filters.
Not sure if it's been pointed out yet, but due to the abnormally short PCBs on the new Nvidia FE cards, I think once EK and others start coming out with FE-model waterblocks we'll be able to fit some pretty high-performance GPUs in cases like the P-ATX and N-ATX. For comparison whereas cards like the 2080ti FE had PCBs of the full-length 267 mm, the 3090 FE (apparently) has a PCB of only about 200 mm due to the new cooler design. Given the lack of SFF-friendly GPUs in Ampere (and we'll see if **Big** Navi is any smaller, but I doubt it), watercooling the FE cards may be the way to go assuming you can actually get one.
I think that kind of config would work pretty nicely in the N-ATX given the radiator compatibility and being able to put the GPU in the upper position.
Only issue I see with the 3090 might be that they put a full triple-slot IO bracket on the card outputs, despite having only one row of ports. It looks like the bracket for the 3080 or 3070 could be substituted (the screw holes look like they line up in a side by side picture), but how you'd get your hands on an extra one without purchasing a whole extra GPU would be a challenge, I'd think.