This assumes the boundary between Python and the native code is clean and rarely crossed.

I've never understood this. Python cannot be optimized like C, C++ or Rust. It cannot do advanced functional things like OCaml, Haskell or Scala. It cannot run in browsers like TypeScript. It cannot do games programming like C# and it can't do crazy macro stuff like Clojure. I don't think it's even second best at those things.

I'm reading this as, "It cannot do things the best", and that's correct. It can't.

But it can do them well enough, and enough people know it that they can drag a solution across the line in most domains.

Sure, Python has types as part of the syntax, but Python doesn't have types like Java, C#, etc. have types. They are not pervasive and the semantics are not locked down.

This surprises me.

If you want the .NET ecosystem and GC conveniences, there is already F#. If you want no GC and RAII-style control, then you would already pick Rust.