Wiki¶

Using ST-tools to flash images to SPI would be really nice. The Bootloader protocol is not that complicated.
https://www.st.com/en/development-tools/stm32cubeprog.html
https://www.st.com/resource/en/application_note/an3155-usart-protocol-used-in-the-stm32-bootloader-stmicroelectronics.pdf