Here's my experience...
Several months ago I upgraded my cheap tablet to a K1. I began using the K1 for flight and regulated the cheap tablet (see sig) for Flytrex Live 3G. And early on, I had found that the K1 would not automatically reconnect to the Phantom's wifi if the wifi signal was broken but later became available. So what I would do is grab my other tablet, drop the flytrex app, launch my flight app, and it would instantly connect to the Phantom via its wifi. I could then fly FPV with my second tablet on the same flight I had started with the first tablet - instantly and seamlessly.
What I learned later is the K1 wouldn't reconnect because the signal it senses from the Phantom was not an internet signal (and it is programmed to assume I don't want that signal since it's not internet), but I could reconnect manually by going to Settings in the K1.
So the question is, would my cheap tablet have displayed the FPV screen via the flight app if the K1 happened to be connected?
I don't know.
I know there is some sort of "handshake" that goes on re FPV, but I don't know if it's between the Phantom and the range extender of the controller, or if it also involves the tablet. I have a feeling the handshake may not involve the tablet.
I will test this in a day or two or three.