It's really great to be able to skip compiling LLVM when bootstrapping a whole OS/toolchain from source and only Rust happens to pull LLVM in.
Besides the gcc work I'm actually also hoping for the rustc_codegen_cranelift work to land one day!
For proper bootstrapping I'm looking forward to gccrs (https://github.com/Rust-GCC/gccrs) alongside mrustc.