I'm latching onto a non-main argument to be pedantic, but I'd like to mention that Rust is fine for _non-embedded_ kernel development too, in my experience.
As you're likely aware, Rust for embedded sucks when there's no HAL, but should be pretty pleasant otherwise. Have you looked into the cortex-a[1] crate?
Some unnecessary instructions could also be a part of an ongoing optimization effort[2][3].