iPhone 7 Plus offers a larger 5.5-inch Retina HD screen with a resolution of 1920 x 1080 pixel which is fabulous to enjoy videos and movies on it.
Can PS3 play MKV? The answer is "NO". The simplest way to get MKV with PS3 is to convert MKV to MP4 or other formats that PS3 supported.
You can use a VR video converter to convert 2D video to VR video or convert VR video for specific VR device like HTC Vive, Samsung Gear VR and Oculus Rift.