Unless anyone in this chat has a degree or higher in human biology, it's doubtful anyone here can speak with any authority on the subject. Not that real education and information stops people from believing whatever they want these days anyways.
But youre right. Internal/External plumbing features are only an indicator of biological sex. Some are born with neither. Some are born with both. Those in the latter two categories are very very very very few and far beween. When you're talking about choromosomes though, generally people born with internal plumbing are XX. People with external fixtures are generally XY. X and Y are generally referred to as the sex chromosomes. XY and XX cover like the vast vast vast majority of humans
However, there are extremely small numbers of people that have XXY, XYY and even XXX
There are smaller numbers still that have XXYY, XXXY and XXXX
There are smaller numbers still that have XXXXY and XXXXX
Whether or not those choromosomal abnormalities are ones that might cause comeone to be outwardly male or female, but "feel" like the other biological sex, ie transgenderism, homosexuality, bisexuality, asexuality...... who knows. There's multiple factors that go on in the process of fertilization of eggs and chromosomes being passed from father to mother all the way up to urine in the womb that impact a fetus's levels of estrogen and testosterone, which also may be factors.
Science doesnt know yet. But they do know all of the above exist.
Im just going to enjoy the shitshow until the mods scrub these posts.