When we first wrote about the 10-cent CH32V003 RISC-V MCU it was offered in a $7 development board and the closed-source MounRiver Studio IDE had to be used for programming. But things have improved since October 2022, and now, you can buy a CH32V003 board for as little as $1.5 plus shipping, and an open-source GCC toolchain and flasher/downloader are now available.