Opening it up, the processor is identified as an STM32F103, and the connection needed to place it in bootloader mode is identified. Then it can be programmed from the Arduino IDE, even though its ...

and an STM32F103. The STM32 appears to be dedicated to providing the board with USB to UART translation, something the first RISC-V compatible Arduino solved with an FTDI chip. Using an FTDI chip ...