I don't believe this has been mentioned anywhere. I went thru the box to see if I could answer the cable question (still no). There is small manual and it mentions LG split screen macOS application.
I haven't installed it yet, and might not, but it seems interesting. You might be able to have two video sources, and put a second video in a PiP source.
"OnScreen Control allows you to easily control the screen configuration for easy customizing workspace on the screen with a few clicks of mouse. In addition, upgraded Screen Split (with PIP Mode) and My Display Presets are all designed for the best, most efficient professional work environment."
I can't seem to link to it. Go to LG.com, and search for "Split Screen". This is actually a welcome surprise. I might try it with a Raspberry Pi I have kicking around.
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People tend to leave reviews when they are angry. I am quite happy with my 4K so Im not going to bother leaving a review. 3 negative reviews, for a product that likely sold thousands upon thousands is amazing.