Polanduino is a Raspberry Pi RP2040 evaluation board with classic Arduino Uno form factor, which has features, as following:

PCB dimensions: 68,58 x 53,34 mm,
all 30 GPIO pins connected to the pin header (Arduino Uno standard with extra 8 GPIO pins),
2-layer PCB board,
onboard: 8MB QSPI Flash (WSON8 package), 12MHz oscillator, PWR LED,
RESET/BOOT switches,
USB-C interface for power supply, debugging MCU and for flashing SPI memory,
DC barrel jack for power supply (12VDC default).

Project published as Open Source Hardware (OSHW) under CERN OHL v1.2 (Open Hardware Licence).

Project has been certified as Open Source Hardware by the Open Source Hardware Association (OSHWA). UID is: PL000012.

More: https://github.com/mfolejewski/Polanduino

This project is the part of Trinity Project (set of three RP2040 evaluation boards):
https://hackaday.io/project/188809-trinity-project

Suggested retail price: 19 EUR + VAT.