Oh it’s possible and people do it in embedded all the time at great expense, but that safety isn’t assured by using a “safe” language, it comes from the requirements, documentation and verification process. OpenBSD’s kernel was developed with security in mind but not that level of safety.
Not really sure what you mean? You have to use `unsafe` in Rust to access arbitrary mutable pointers. How would you do DMA, or write a device driver, without `* mut T`