@vertigo don't have much experience with microcontrollers, but ended up debugging low-level stuff multiple times and usually I was looking at disassembly and single-stepping instructions regardless of what language the software was written it.
The only way Rust could make it more difficult that I can think of is by spitting out horrible instructions that make the disassembly unreadable. But unreadable assembly is also usually suboptimal so I think they'd try to not do that...