Maybe compile speeds suffer, but I've forked this guys work to make a mini special-purpose OS for x86_64 machines, all in rust (except 2 screens of assembly):
Discussion
Didn't know about this 👀 Have you heard about RedoxOS? It's microkernels + rust
Yes. I was skeptical of redox from the start because it happened so fast and I doubted anybody could achieve those results so quickly. But it's been a long time now and nobody has called him out as a fraud (that I am aware of) so I guess I should be very impressed. He matched the ABI and syscalls to linux so that existing software would run on it as if it were linux.