Just to recap everything from Foxconn, with absolute certainty:
Die size is 100mm^2, with a 200mm^2 GPU in new dev unit dock (similar setup to medium range px2, and confirmed gp106). While gp108 might be 132mm^2, it has 768 cuda cores. Further, the soc could have a stacked orientation. In this case, we should expect performance better than tegra x2.
6.8'' screen, not sure about resolution due to eye observation.
Dock gives no significant boost to ps4 pro level. Provide better cooling components but the fans are in the tablet.
4000+ mAh.
1.7+ GHz quad core, clock closer to a57 but stated to be a73. 921 MHz gpu, core count unknown.
Very stable performance with Unity fish demo. Less than superb lighting.
Conclusion: Massively more powerful compared to the wii u.