YY is non viable; the X chromosome has many genes which are essential. You can be XY, female, and fertile, but it’s pretty rare.

XY females aren’t always sterile! Most of the cases we know of are sterile though, because you don’t get tested for this stuff unless something’s wrong (the woman in the case study got tested because XY women are common in her family, her daughter is XY).

Mothers always pass the X chromosome due to how the egg works from what I remember. The sperm determines whether you get x or y for the second part.

There is a rare event where you can have multiple sex chromosomes, like XYY, but the X is always present (at least for humans). Considering the genes in an X chromosome are vital to life, even if we could artificially create YY, it would probably end up nonviable