The answer to this question is not as clear cut as one may think. There are many instances where Bingo is depicted as a boy, such as when he is shown wearing a blue shirt and playing with other boys. However, there are also instances where Bingo is depicted as a girl, such as when he is shown wearing a blue dress and playing with other girls. It seems that the answer to this question depends on the individual artist or cartoonist who created the particular depiction of Bingo.
So, it is difficult to say definitively whether Bingo is a boy or a girl in bluey. However, it seems safe to say that he is an ambiguous character who can be portrayed in many different ways.