Correct me if I'm wrong dirbaio, but my understanding is:

* embassy-stm32 doesn't support cases where some hardware is pre-initialized (it assumes default state mostly)
* There IS desire to support it, but nobody has done it yet/proposed a mechanism for it
* It's almost certainly something that would be need to be done *inside* embassy-stm32: you'd have to (carefully) poke some hidden items to set things normally set by `init`