I second @JaromandaX's question. I have old LG TV. The LG CEC is so bad, I installed CEC blockers on all inputs.

Would be much better if you linked to exactly what you have. And where you got your Raspberry Pi operating system and display application from. We don't know what OS you are running let alone what application you are using to display images on your LED matrix. We don't even know what you expect to see on your LED matrix.

Interesting. Didn't know that. Well, if it's possible then you could cut open the USB between the RPi and PC. Cut the positive wire in half and tap into the ground wire (leaving the ground of the PC USB port connected to the ground of the RPi USB port. Then connect the positive wire from the RPi USB port to a appropriately sized power supply for the RPi you are using. Also, as you suggested, you might find a USB power hub that can do the same (allow PC USB data lines to connect to the RPi wile supplying an alternative source of power).

e-ink displays are used to lower energy cost. Usually on battery operated devices. RPi's have a high energy cost. Even the Zero.

I don't want to encourage you to stay here as this is a general Linux question. So add a comment if you have moved this to a different stackexchange group. Going on, most Linux distros are setup as work stations or personal computers. Is sounds like you want a Kiosk (i.e. complete autonomous or remote control of the screen). There are plenty of Linux / Kiosk howtos.

Just a quick guess before putting in too much more effort. Are you sure there is nothing else on the network with the same IP address? Try disconnecting the Raspberry Pi and pinging it's IP address from another still connected computer just to make sure there is no answer.

@me.at.coding, you have a rep of over 17k on stackoverflow.com. You probably already know what overhead an interpreted language like Python needs. So, is this really an embedded question (doesn't really deal w/RPis)? If so, the quick answer is that companies go embedded to save (production) money. Software isn't free, but a lot of companies act so. So, maybe, the real question ... can Python survive a constant push to get the BOM cost down. Maybe you can get Python to run on a $30 processor. But what about a $10 processor?

Stop. I concede it may not be 100 times. However I've heard some say as much as 1000. I think the best answer to this debate can be found here in this stackexchange Q/A. Which echos your sentiment of using the appropriate tool for the task. Back to the question here. You can use a form of Python on an embedded processor. But you might find it more expensive in the long run.

Got a feeling you are new to this. Python is an interpreted language. So you need a lot of already loaded up and running software to interpret the Python software. That takes space most $5 and less microprocessors can not spare. That is why people use compiled languages like C. I think you already know this. But just in case, a compiled language turns code into executable files specifically for the target processor. In some cases, all you need is to "burn" the executable file into the embedded processor and you are off and running. If that's not bad enough, python runs ~100s of times slower.

The camera appears to be advertised to work with all Raspberry Pis but it wouldn't hurt to add that information to the question. Also a picture might help. If, for nothing else to check if the ribbon cable looks to be installed correctly (not backwards) and is well seated. If it is suppose to work, perhaps it is time to try different hardware. Do you have another Raspberry Pi you could try?

Since you are not saying how well synchronized the video has to be (i.e. frames no further apart than, say, 100ms) or how you are going to manage to simultaneously play them back synchronously (did you even think about playing them back?) ... well, then, the answers are open to all kinds of interpretation. So here's one: Forget about building anything with a Raspberry Pi. Just buy a high resolution multiple security camera system. All the videos will have time stamp overlays. How you play them back synchronously is up to you.

"... I am open to all solutions"... Again, have no idea what "closely synchronized" means from your perspective. And most RPis have 4 USB ports. But even the most casual user understands USB hubs can be used to expand any computer's USB capabilities. It is starting to sound like there are many unknowns for this project. None of the dozens of stackexchange web sites are setup for discussions. Only for 1 concise question and well thought out answers per post.

Why use 2 RPis? Why not get 4 USB cameras and use 1 RPi? And, likely, many will ask "how closely synchronized"? It may be your (missing key) requirement is so difficult that an OS (LInux/Windows/Unix) is not a good solution.

I think you are using the RPi as USB Host and the S24 as USB Device and likely USB/MTP. Then you want the use the S24 as a USB Host for more peripherals of unknown protocols? USB is flexible. However I do not think you can use the same device both as a USB Host and USB Device simultaneously. Actually, I don't think you can have more than 1 USB Host. Further, I think USB Hubs only operate in one direction. They are plugged into the USB Host using a plug and USB Devices are plugged into the USB Hubs using a socket.

Regarding the data to control the LEDs, have you looked into how well a SBC can create time sensitive data strings? Since most SBC run dozens of programs simultaneously, they can struggle to create time sensitive signals. Addressable LEDs might do unexpected things and servo motors might jitter. I think there are ways to mitigate these problems. But leaving this comment just so you aware of the possibilities.