I found some old pictures of this project, for which I was quite satisfied, so I decided to put a last log on it.

After the project was done and fun enough for the whole house, I got motivated to improve it, thanks also being a RevSpace member back then. From SHA2017, they got tons of leftover badges (afterall, they were made there...). They look like this on the outside:

With a bit of X-ray power, looking through them shows sacrificable parts:

You guessed which one? The hint is in the following picture:

Exactly, I just needed the interfaces for power and control the same LEDs like before with the Arduino Nano and no more, while needing more space. Who knew that a handsaw would give you a free small ESP32 development board!

The sketch works by getting through a "simple" (not for an 8-bit MCU guy tho) REST protocol, the string to show through the LEDs. This was quickly doable thank to the aREST library.
One can connect to its address from the local network, which set in the code below, put the text on the web page, and click send. This was implemented in a simple Android app for sake of simplicity, for which I don't have the code anymore, but I still have the sketchy ESP32 code, linked below.

The snippet is here.

That's all for now.