Very cool!

I think the hat will essentially handle the hard parts of driving the display. I would be surprised if the Pi4 would work very hard. You talk to hat, hat talks to LED matrix.

This is the Python driver: GitHub - hzeller/rpi-rgb-led-matrix: Controlling up to three chains of 64x64, 32x32, 16x32 or similar RGB LED displays using Raspberry Pi GPIO · GitHub

You can either port that to Elixir or ensure you can run it on Nerves and talk to it from Elixir. You could go wild and try cocoa’s pythonx library to avoid needing to poke around with Python support on the Nerves system (semi-advanced), we do not include Python by default. Porting to Elixir is the boss move but more time-consuming so depends on what you want to do.

If porting, yes. Probably circuits GPIO, I didn’t dig in to check if the driver uses more common protocols (I2C, SPI, etc).