One issue with STM devices is the shear amount of peripheral implementations, e.g. at least 3 USART implementations over the years, with all kinds of small diff

One issue with STM devices is the shear amount of peripheral implementations, e.g. at least 3 USART implementations over the years, with all kinds of small differences. Pair this with inconsistent SVD files and you are halfway to the current HAL situation. It's intended for async usage, but take a look at embassy-rs (not yet on crates right now) The embassy contributors put a ton of work into unifying the pac for different versions of the peripherals and called it metapac