Why would this matter? The borrowck is (a) not needed during bring-up because as its name suggests it is merely a check, so going without it just means you can

Why would this matter? The borrowck is (a) not needed during bring-up because as its name suggests it is merely a check, so going without it just means you can write nonsense and then unbounded undefined behaviour results, but (b) written entirely in Rust so you can just compile it with the rest of this "exotic hardware" Rust compiler you've built.