The pipe symbol | is used to represent Union in versions 3.10+.
Union[str, int] can be abbreviated as str | int.
Additionally, Optional[T] can be simplified to T | None making use of union.
Of course, I realize that readability should take precedence over conciseness.
My suggestion is to introduce a syntax like T? to abbreviate Optional[T]. Sorry if this is not a good proposal; please let me know of the problems with it.