Python is often used as (very useful!) glue for calling CUDA, C, C++, Fortran, etc… codes.

So, if you are thinking about the sort of “business logic” that’s often Python, but the performance comes from the parts that are usually not.

As glue language for the actual work implemented in a mix of C, C++, Fortran and more recently Rust.

Just that Python culture has a strange way to call bindings to native code, "Python libraries".

Yes, but the numerical backend of the python libraries are written in lower-level languages. For example, pytorch uses a C++ backend.

You heard correctly. This discussion is about C++ though.

Bumblebees shouldn’t be able to fly; they do anyways.