DFU is Device Firmware Update mode - that's a way to update firmware via the same USB cable you use for rusEFI communication. stm32 DFU is part of stm32 factory bootloader and we expect that any rusEFI board could be updated/reset via same USB connector as the one you use to communicate to your rusEFI ECU. Please let us know if that's not the case!
A: As of Aug 2021 rusEFI console uses "older" ST DFU driver. You would need to remove newer "STM32 BOOTLOADER" driver. Hit "Remove Device" with "Remove Drivers" checkbox. Once you've removed newer "STM32 BOOTLOADER" driver re-install DFU driver using rusEFI console driver button. Direct driver link https://github.com/rusefi/rusefi/files/7273342/ST.Microelectronics-3.0.4.0.zip
Some boards have [Tag-Connect-TC2030] upwards three of those! Some boards have an unofficial (?) ST-Link V2 pinout. Both are intended for software developers while debugging issues, those are not intended for firmware update/recovery.