I'd recommend setting them up in parallel and using this fantastic driver: https://iosoft.blog/2020/09/29/raspberry-pi-multi-channel-ws... . Anecdotally I was able to drive 16 200 pixel strings at ~180Hz with a Raspi 4B.

Running in series with the regular adafruit library would work as well but at this number of pixels the refresh rate might start to get a bit choppy, and you probably want to add power in the middle of the string regardless so the wiring isn't any harder.

That's really neat! I have all 1536 LEDs in a single string and that definitely is a limiter in terms of framerate but the resolution is so coarse that this hasn't been a problem (so far). But this driver takes it to a completely different level. Unfortunately the Pi Pico (which I would have liked to use) only does 3 A/D channels so that would have ruled out two player games with full x/y control. Fixing that and some other issues would require much more hardware work and I want it to be so simple that even a novice (motivated 12 year old) has a chance of putting it all together.

Connect the led strip data pin to an available Io pin on the pi, connect the strips and to pi gnd pin and to a 5V power supply gnd pin, and connect the strips + to the 5V power supply.

Then use a library on the pi, for example this: https://github.com/jgarff/rpi_ws281x

They are the most common type of addressable WS2812 (AKA NeoPixel) LEDs. Type that into Google, choose a library.

I used the Arduino FastLED library. You need to use the very latest one for R4 support.

For the software check for WLED and FASTLED