Long story short, I found a Thinkvision M14 lying around at work and decided to try it with the Deck. Works really well, does PD passthrough via USB-C so I only need Deck -> Display -> Power adapter via USB-C cables.
It got me wondering if I could pick up an OLED or otherwise better portable...
CEATIC 2016: Sharp Showcases 27-inch 8K 120Hz IGZO Monitor with HDR, also 1000 PPI for VR
It requires 8 DisplayPort cables! 27" 8K is approximately 328 PPI. Maximum brightness for HDR was quoted at 1000 nits.
Also shown were a pair of displays intended for 4K VR at 1008 PPI per eye.