As one of the other quotes suggested: fork the kernel project and rewrite it entirely in Rust
That’s not practically possible given the scale of the kernel. And doing a total rewrite is almost always a recipe for getting stuck and, if you ever create anything, creating something worse.
Replacing C with Rust in the upstream kernel is akin to replacing the engine in a car while it’s running or being used every day.
Almost all real-world software development is like this. That’s what we do.