The blue pill board has to be programmed once using an STM32 programmer. After that, you can use most standard Forth words and also use some that can manipulate the low-level microcontroller ...

[Wassim’s] interest in STM32 was spurred by the Blue Pill board–the $2 STM32 board and his desire to debug it. He found you often have to make tweaks to the IDEs to get them to work.