As suggested by @Vitaliy_Kiselev I've moved this into it's own topic, originally here. @lenuisible Thanks for the original work on the GH3 Web Controller.
Maybe someone here uses the GH4 for filmmaking and wants to use their iPhone as a wireless monitor. In that case you're like me, but lucky enough I'm a developer ... so I just wanted to let people know that I'm working on a viewfinder app just like that.
It's still a prototype for now, but if you're interested in following the development I suggest following me on twitter (marcusstenbeck).