> I wonder how is the experience writing Rust or Zig with LLMs

I've had no issues with Rust, mostly (99% of the time) using codex with gpt-5.2 xhigh and does as well as any other language. Not sure why you think compile times would be an issue, the LLM doesn't really care if it takes 1 minute or 1 hour to compile, it's more of a "your hardware + project" issue than about the LLMs. Also haven't found it to struggle with borrow checker, if it screw up it sees the compilation errors, fixes it, just like with any other languages I've tried to use with LLMs.