Shared via mypy Playground

main.py

from typing import TypeVar, Union

T = TypeVar("T")

Thing = Union[str, int]

MaybeTuple = Union[T, tuple[T]]

def untuple(item: MaybeTuple[T]) -> T:
    if isinstance(item, tuple):
        return item[0]
    return item


def test_func(var: MaybeTuple[Thing]):
    reveal_type(untuple(var))  # object in mypy, str | int (==Thing) in pyright