How can I use my LG K8 as a monitor for my raspberry pi? I would like to use my raspberry pi outside, which is only currently possible with the official touch screen. This is inadequate as the screen is a large unit and thus it is not portable enough. I would prefer it if the solution was wired.
Mobile screen has not any video input port which can be accessed easily so you can not use smartphone screen as the monitor.

You will require HDMI to screen ribbon cable converter which is neither standard nor available.

Edit:  You can start a vnc server on Raspberry Pi and connect both on same network. VNC viewer app

Or Use mobile to ssh into odroid and for X server forwarding use X Server XSDL app