Ok from a distance this product is attractive, an android tablet with HDMI in, 500nit brightness, etc...  Upon research I can tell it will not be powerful enough to provide a good experience with the go4 app but it may be usable with the djigo app.  You android enthusiast may even be able to tune it up to provide a better experience not sure as I don't have one in hand.  I have been searching for a nice little HD LCD with HDMI input and internal battery to use as a secondary display to take advantage of the HDMI out.  If you have ever used a tablet/crystalsky with a secondary display through HDMI you would understand that its nice to have the uninterrupted camera feed always visible.

http://amzn.to/2zhzgE6
http://www.flysight.com/index.php?ac=article&at=read&did=18


Next best option would be a field monitor like this one. it's also 500nit.

http://amzn.to/2yJCCw3


GeChic also makes Hd LCDs, but 350nit or lower brightness so not the best option.

If you found any of this at all helpful let me know with the little  thumbs up.------->---->-->---V

Wanna ask. Will it work with wireless hdmi? Wanna to conect with PC without cables