These P* matrix panels are looking more and more interesting. Does anyone have any leads on how to drive (and power) a substantial display comprising 100 panels of e.g. 64x32 to form one big display? That’s clearly beyond the arduino capabilities.
SmartMatrix can drive a few of these displays at once with a single Teensy 3.2: https://github.com/pixelmatix/SmartMatrix
This project claims to be able to drive up to 96 panels on a single Raspberry Pi, at 100Hz refresh rates: https://github.com/hzeller/rpi-rgb-led-matrix
Regarding power, you’ll need up to 8A per panel, so 800A (4kW) for 100 panels. Be careful, start small. 
Go for the raspberry pi design. Microcontrollers are definitely lacking of memory for large displays with thousands of pixels. Thus the raspberry outputs the required 5 volts signal. You don’t need the shift register.