This has now been done and should work client side.
>>> dict_a = {'a': 1}
>>> dict_b = {'a': 2, 'b': 3}
>>> {**dict_a, **dict_b}
{'a': 2, 'b': 3}
Another related feature on the client side that also works is pep584:
>>> dict_a = {'a': 1}
>>> dict_a |= {'a': 2, 'b': 3} # equivalent to dict_a.update(dict_b)
>>> dict_a
{'a': 2, 'b': 3}
>>> dict_a = {'a': 1} | {'a': 2, 'b': 3} # equivalent to dict(dict_a, **dict_b)
>>> dict_a
{'a': 2, 'b': 3}
linking: