This is the same as asking for typed JS and getting Rust recommended just because the syntax is similar.

They are totally different, the core paradigm of programming is totally changed and most of the points of JS are not in Rust (meta-programming, garbage collection, community)

You can add typing to an existing codebase, saving you vast amounts of work compared to rewriting in a different language.

Can that really be done for Python and the vast amount of libraries? I don't get the sense that one could simply slap on a static type system on Python and get libraries typed for free.

That is unless we're talking about a gradual typing system for Python, where new Python code could be typed and integrated into untyped codebases, similar to Racket and Typed Racket.

The existing type system (see e.g. http://mypy-lang.org/) is gradual. You can mix typed and untyped code, at the cost of some safety.

You can also write type stubs for libraries that don't provide type information.