you have your numbers wrong, display is
5120x 2160 , ratio is 2.37 ≈ 21/9 (Close enough - Marketers don't like large numbers like 64:27)
No where is it 2560 resolution we typically see on 1440p panels for the width. but it has the traditonal 4k height of 2160p with the 5k width.
I am interested in purchasing this, maybe when its a 1/4 of the price or if I can get my company to buy it for me