> XX instead of XY. The fact that 1 in a million people is neither a man or a women has no bearing on this fact.

Using the typical assignment of “sex” (really, a kind of gender ascribed based on a subset of sex traits at birth):

1 in 25,000 men is XX (approximately universally infertile, though chimerism might affect this, I guess)

1 in 15,000 women is XY (potentially fertile with HRT, and in at least one documented case, due to chimerism, without.)

As a strict definition that's fine in a context.

However:

> The fact that 1 in a million people is neither a man or a women

the number you are looking for here (ie only ..

    conditions in which chromosomal sex is inconsistent with phenotypic sex, or in which the phenotype is not classifiable as either male or female

) is 180 in a million, or some 4,625 or so in a country such as Australia - which does have some real bearing on things such as national passports and why Australia has a three value gender field there ( M | F | X ).

Less strictly, the prevalence of "nondimorphic sexual development" might be as high as 1.7% or 17,000 in a million.

[1] https://en.wikipedia.org/wiki/Intersex