Seems like a fairly loaded question. People of all sexualities share their sexual preferences constantly, and always have, any time they refer to their partner or spouse.

A man at work mentions his wife, he is thereby telling people that he is straight.

A woman mentions her girlfriend, thereby telling people she is a lesbian.

A boy say “I’m gay” in public and he is doing the same thing as the first two examples but in a slightly more direct way. All of these things are equally acceptable and, for straight people, they always have been.

Telling children about the existence of sexualities, whatever they are, is acceptable too. I can’t think of any reason why it wouldn’t be. Kids can understand mummies and daddies so why on earth would they not be able to understand, or it be problematic to tell them about, the existence of LGBTQ+ people?