Requirement: Keep BOOT0 held high so the STM32 is in DFU mode upon initial connection to computer. The computer software can either flash or leave immediately to 0x08000000 running the flash program.
Issue: The DFU leave command does not work while BOOT0 is held high.
Potential Solutions: Users have solved this issue on STMF4 products due to it having a Cortex-M3/M4 https://community.st.com/t5/stm32-mcus-embedded-software/leave-dfu-while-boot0-is-high-stm32f4/td-p/556307
Uncommenting this lines solves the issue on those products as well.
#define USER_VECT_TAB_ADDRESS
However I haven't found resources with a step by step solution for Cortex-M0 (STM32F072RBT)
I have tried relocating the vector tables and booting from SRAM. However, since I never found a clear way of doing this I believe all my attempts had corrupted code.
Large Picture Motivation: Release a product (STM32F072RBT) with no buttons or toggles on the PCB and allow customers to flash and interact with their product over USB serial interface.
Sorry I thought I had deleted the post prior to approval. This is the answer: Located in system_stm32f0xx.c or whatever your Cortex-M0 chips name is
void SystemInit(void) { SYSCFG->CFGR1 &= ~(0x1 << 5); }
Hopefully this will help someone else out!