Reverse HDMI splitter

Does anyone know of a device that can take 4 HDMI signals in and convert them to a single output?  My kids and their friends love to play nintendo switch, and trying to see if there's a way to feed the signal from 4 docking stations into one TV for a split screen output on a single monitor.   Would also be useful for watching multiple sports games from Tivo minis, etc.

Thanks!