@lore That's just how Embedded Systems work in general. If you want good documentation and clear instructions, look into Mr. Lee's publications. I don't recall him working with the ST series but his work with competing hardware is legendary. There are too many to list. I know that he worked with Nordic Semi hardware as part of the PineTime effort.
As for the ST hardware, I just used it to make a BMP. I would recommend using an existing project to get it mostly functional and go from there. Maybe look at some of Mr. Lee's work with MCUs to find some useful tools and perhaps some MCUs that you can use in the future.
I've seen non functional hardware go from nothing to functional when he was involved. Open Source tools emerged on previously closed source platforms and obscure products were documented and made to be functional.