[Vultra]

For me it worked I run NEThunter OS on my one plus3t, I added my old one plus3 which was lying around as a Bluetooth gamepad, now it works more* like a 3DS. I’d be glad to share my setup if anyone uses oneplus.

Coming to the Expanded-screen issue..
I totally assume* there will be issues like accessing the display at the bezel trying to push things from one screen to another. As in our setup both phones are either connected by wifi or Bluetooth. Unlike the ZTE Axon OP has mentioned. Even if we manage to do everything we will still experience the same lag we experience with the “Screen-sharing”

I assumed the OPs request was to game on one and do YouTube on another. Thus he doesn’t need both phones running on a synergy.

For me it looks like you want to run them together as one. Which I think is hard to pull off (still possible if you don’t mind the lag)
Correct me if I’m wrong about these assumption It might be my English to blame.

Yes, that's it. NEThunter. thanks mate.