This highlights file should live in <nvim-conf>/after/queries/python/highlights.scm.

Please note that with neovim 0.8, for files which queries extend existing queries, you need to add ; extends at the top of the file (see this discussion).

Here is some Python file:

"""Test conceal."""

import math
from math import sqrt

for element in [0, 1, 2]:
    print(element)
    _ = element or False
    _ = element and True
    _ = element != False
    _ = element not in ["a"]
    _ = 1 * 2
    _ = not True
    sum([1, 2, 3])
    all([True, True])
    any([True, False])
    _ = 1 + math.sqrt(16)
    _ = 1 + sqrt(16)
    _ = 1 + math.pi
    _ = lambda x: x + 1
    _ = len([1, 2, 3])
    _ = None
    int(3)
    float(3)


def func(x: int, y: float) -> float:
    """Increment."""
    return x + y

and how this looks when concealed