There's nothing about Arduinos there... the project uses an Adafruit board based on the RP2040 microcontroller (the one of the Raspberry Pi pico). I guess they used "Arduino" to mean "microcontroller board".
I came here just to write this... As the co-founder of Arduino I find this use of Arduino as a generic "microcontroller board" or "not a raspberry pi" a bit shocking.. :)
You're up there with Google, Hoover, Xerox... bask in it :)
Isn’t Arduino both a hardware term and a software term? I’m working with a nRF52840 board, but I’m using the Arduino IDE to author Arduino code to run on it.
Yes it is. The Arduino framework has been ported to many platforms. However, the OP is about CircuitPython, not using any Arduino software.
Be proud. You started an ecosystem that's taking over the Embedded world :-)
If it's any consolation, everyone seems to feel the need to invent a new word for daughterboard for their own flavor of microcontroller / single board computer.
For a second I though that maybe they meant UI, but no, they used circuit python too