Looking for an HDMI multiplexer / multiviewer for couch gaming

Hello everyone, I have a fairly large TV running 4k @ 120hz, and I'm looking for a multiplexer / multiviewer for for couch gaming split screen (vertical / horizontal) or quad screen with multiple pcs / steam decks / consoles. I don't know much about hardware HDMI multiplexers or multi viewers. I've seen some on amazon, but they seem to not really be gaming focused or support high resolution and refresh rate, and the screen layout doesn't appear to be configurable. I've attached some sample layouts that I'm looking for, however the main one I'm looking for is two horizontal screens. I haven't found a multiplexer / multiviewer that supports two ultrawide displays stacked vertically, however I think that should work with two pc's or steamdecks for example. Are there any devices that could achieve these configurations? Would it be better to build a dedicated PC with input capture cards? I'm also using eARC for audio to some sonos devices if that complicates things. Let me know your thoughts or recommendations!

4 Screen Grid

3 Screen

2 Screen Vertical

2 Screen Horizontal