Most Python libraries that relies on C are numerical stuff.

From experience with this type of code you typically end up with a load of functions that take in a numpy array and its length/dimensions to a C function that works on that array in place or an output array that was also supplied. In terms of getting this wrong, it’s usually a crash caused by out of bounds memory access which would still be a runtime crash in Rust. So I’m not sure there’s a massive benefit for these types of code other than the fun of learning Rust. Other than that, you’re typically writing C/C++ to interface with C and Fortran libraries that are really battle tested, and for which it will take decades for Rust to have equivalents. So moving to Rust will just cause you to have lots of unsafe statements - not a bad thing necessarily if you are doing a lot of work at the C level in existing code but less of a benefit if you are doing a straight wrap of a library.

On the flip side, things on the web side of Python like uWSGI which is written in C are important for the security aspect but they’re a very small part of the Python ecosystem.