In theory you could have this scenario. 5 screens with apple tv 4ks. Ethernet cable back to a 1gb switch. X Box, Playstation, Gaming PC, 2x laptops. All devices can output and input NDI… thus you can send anything to anything. To put that in as a vision matrix would be considerably more expensive and time consuming.
If you then drop in a birddog NDI convertor with a loop out you can take a PGM and then use the convertor to create an NDI source that can go anywhere.
Expand that to a vlarge multi room venue and you can injest a local show and use the venue network backbone to distribute a plenary to multiple breakouts etc etc. Run a Skype or zoom server (all NDI) etc etc