Thank you for the references to those similar issues - turns out that I might have the same problem as zouden - it does compile, both with Serial and SerialUSB, but it doesn’t really open that port on the USB-C.
I’ve forgotten to mention the board_build.offset = 0x8000, which I was using and it does flash correctly via SD card, I can see it being copied to the right place in the STM32CubeProgrammer.
I’ve tried using the linker script STM32F446ZETx_FLASH.ld but I feel like it won’t be as easy as that - yes, I have no clue what it does xD kek