Ask HN: Anyone using Python's static typing in a large project?

I would say the opposite, it is not very useful for small projects.

Zulip's post on their experience with mypy got some discussion last year.

Yes, I'm familiar with their post, and it's great that their server code is available on Github [1]. Was hoping to find more projects using it.

Google internally uses pytype, which is similar to mypy, and while not globally used, is used on across a large number of files.