Code available in this git repo.

There is the /OpenBootloader project folder and another folder with a simple blinky code i used as payload for the bootloading process.

Inside OpenBootloader i used the CubeIDE environment.

Output from the logs of CubeProgrammer

  15:16:19 : STM32CubeProgrammer API v2.18.0 | Windows-64Bits 
  15:16:27 : UR connection mode is defined with the HWrst reset mode
  15:16:27 : ST-LINK FW  : V3J8M1B5
  15:16:27 : Voltage     : 0.00V
  15:16:27 : Bridge Freq : 48000 KHz
  15:16:27 : Baudrate    : 125 Kbps
  15:16:27 : BL version  : 2.0
  15:16:27 : Device ID   : 0x469
  15:16:28 : UPLOADING OPTION BYTES DATA ...
  15:16:28 :   Bank          : 0x00
  15:16:28 :   Address       : 0x1fff7800
  15:16:28 :   Size          : 36 Bytes
  15:16:28 :   Bank          : 0x01
  15:16:28 :   Address       : 0x1ffff808
  15:16:28 :   Size          : 36 Bytes
  15:16:28 :   Bank          : 0x02
  15:16:28 :   Address       : 0x1fff7828
  15:16:28 :   Size          : 4 Bytes
  15:16:28 :   Bank          : 0x03
  15:16:28 :   Address       : 0x1ffff828
  15:16:28 :   Size          : 8 Bytes
  15:16:28 : UPLOADING ...
  15:16:28 :   Size          : 1024 Bytes
  15:16:28 :   Address       : 0x8000000
  15:16:28 : Read progress:
  15:16:28 : Data read successfully
  15:16:28 : Time elapsed during the read operation is: 00:00:00.208
  15:16:49 : Opening and parsing file: nucleog474_blinky.elf
  15:16:49 : Memory Programming ...
  15:16:49 :   File          : nucleog474_blinky.elf
  15:16:49 :   Size          : 5.80 KB 
  15:16:49 :   Address       : 0x08008000 
  15:16:49 : Erasing memory corresponding to segment 0:
  15:16:49 : Erasing internal memory sectors [16 18]
  15:16:49 : Download in Progress:
  15:17:06 : File download complete
  15:17:06 : Time elapsed during download operation: 00:00:17.085
  15:17:06 : Verifying ...
  15:17:06 : Read progress:
  15:17:08 : Download verified successfully 
  15:17:08 : RUNNING Program ... 
  15:17:08 :   Address:      : 0x08008000
  15:17:08 : Start operation achieved successfully

 Wiring details https://community.st.com/t5/stm32-mcus-products/stlink-v3-canbus-transceiver-wiring/td-p/764738