caniac

my stuff is in xLights so it might only confuse you. With FPP its just load and go, you don't need to learn Linux to work with it. you should have to mess with the GPIO connections, just add the PiHat and connect your panels (remember the panels are 5V so don't use a 12V power supply or you will see blue smoke). In FPP you just setup the static IP, then setup your output tab (how many panels you are using, how they are connected, etc.). There is an FPP Facebook group with tons of help.

for the time being a P4 is overkill, the 3B+ will more than handle either the colorlight card or PiHat. Scrolling words can be done with a widget in xLights or I would think S5 has something similar (that's the easy part). If you just testing then the Pi and PiHat are the cheaper/easier route to go. I run a 4ft x 4ft and a 3ft x 6ft matrixes in my show and for my application the colorlight card gives me a richer color palette (based on my viewing distance).

Looks good

look to be a pixel grid with one inch spacing, there are several ways to build a matrix, one involves pushing pixels in a pixel mesh and the other using pixel panels (P10 and P5). Panels are a tighter grid (10mm and 5mm respectively). Decision comes down to viewing distance, if your audience is 10-20ft away then the panels are a better choice but at 50ft or more then the mesh has its merits.

I went with a Digital Storm gaming PC mostly for multiple monitor support, 500mb SSD drive, and a 2TB secondary drive for my backups. i7 processor but might have been better off with an i9 though others say the AMD Ryzen chip is faster/better. Spent more than I would have had I gone to BestBuy/WalMart but am happy with my purchase.

I've gone the P10 route, allows me to not only change station on a dime but add messages.

yup "What does the fox say" by Yelvis. Had more than a few flaws in it but shared it none the less. It's funny to see some of those running it now and the flaws are still there!!

Look around at glass/window companies, you can get lexan in any size you want. In my case I had to drive a couple of hours but I was able to get what I needed and they cut it for me (needed it 54" x 54"). you can find raspberry Pi's at Amazon for $35. FPP is a free download and there is no shortage of help configuring it.

there is a Facebook group dedicated to all things P10 and P5

WiredWatts is where I have gotten mine. Crocketts is currently out of stock. If your going big you might also want to check with RayWu.

pixel matrix is something I am building this year for a different application. No real difference in sequencing, to the software its the same item (only difference is the spacing). Tighter the pixel spacing the better the video looks. All a tv really does is display a video on a much tighter pixel grid. Pixel matrix is currently put away. Video needs a device that supports its resolution, doing patterns and designs is low resolution graphics and plays well on pixel matrixes.

at that distance I would stick with P10, no benefit to use P5.

how far is viewing distance?

its not a tv but a P10 panel running 720p video. Big difference is the spacing, the hanging panels I posted are one inch spacing which is the tightest you will find with bullet pixels. P10 is 10mm spacing.