Yea I'm in the same boat. It's nice, though there are definitely warts. For third-party stuff stubs are a big help. For stuff I'm actively working on I've found comments/docstrings (I've used reStructuredText) to be useful:

  self.ivar = 1  # type: int
  
  self.ivar = [1]
  """ :type: list[int] """

  def fun(arg1, arg2):  # type: (int, str) -> str

  def fun(arg):
      """
      :param int or str arg:
      :rtype: str or None
      """

I like the comment version (e.g. `# type: int`) better (plus its officially defined in PEP 484), but sadly they tend not to work as well, sometimes due to not being able to `import typing`, and sometimes for other less clear reasons.