Spanish countries do it for years with "@" or "x" like "estimad@s" for "estimados" and "estimadas" at once. And Latin America is not very politically correct, it's just respectful for all genders.
Otherwise tell me how do you say niñ@s out loud.
In reality, probably “niños y niñas”.
[1]: https://en.wikipedia.org/wiki/Open-mid_central_rounded_vowel