[maleldil]

Annotating empty collections is one of the few places you need to annotate outside function signatures. It's not a big deal. It doesn't happen that often.

[nomel]

And, when it does, you can just put them when the empty container is assigned:

    things: set[tuple[str, str, int]] = set()
    users: list[User] = []

Many people don't seem to know this exists.