I assume you allude to Rust's borrow checker. If you are, your concern is misplaced: which is a common occurrence unfortunately when it comes to this topic. Note that most of the interaction with the borrow checker's rules would be tackled by the interfaces between Rust and C that are being incrementally added to the kernel. By the time the 'end users' (the embedded Linux device driver authors you allude to) are involved, all they are doing is using safe Rust wrappers for loads and stores to MMIO, as an example, where there is no fundamental interaction with the borrow checker (because those happen at another level in the call graph involved).

That said: To appreciate the value Rust provides there is going to be some experience driven knowledge gain needed but the efforts underway should help.