Well to whittle it down, Colin Wright does a good take on the topic of intersex frequency:

https://colinwright.substack.com/p/intersex-is-not-as-common-as-red

Where any clinically meaningful term of intersex results in 0.018% of people, a vanishingly small number. So let's look at that.

Complete AIS... "it's a girl!" Raised as such, has a vulva and a vagina, and usually isn't discovered until puberty when they don't menstruate. Infertile. Female gender identity, heterosexual identity.

Wisniewski AB, Migeon CJ, Meyer-Bahlburg HF, Gearhart JP, Berkovitz GD, Brown TR, Money J. (2000)

So, an unfortunate occurrence, and does need a little medical care, but it's nothing to to with being gay.

You can see from the table there, that after classical congenital adrenal hyperplasia, it drops steeply. So I'll just touch 46,XX CAH. (46,XY CAH does not result in intersex.)

In 46,XX CAH, there is a higher incidence of gender-atypicality, bisexuality, and homosexuality. In extreme cases, the fetus is exposed to higher levels of androgens than a male would be, and you can also get complete genital virulization, such that there is a well-formed penis and scrotum.

This can result in male gender identity, as well, but not frequently. It's rare, sometimes with SRS.

Meyer-Bahlburg, H. F., Dolezal, C., Baker, S. W., & New, M. I. (2008).

So, of the most prevalent phenomena that's actually intersex, the answer as to what intersex has to do with being gay is: a tiny bit. It's really more of an etiological clue to the sex researcher than anything. Certainly does not strike me as a salient social phenomena that would be better served outside the traditional rainbow wrt. non-heterosexuality.

They can just be bisexual or gay... or trans... in the initialism. (My guess is they probably don't really have a salient trans identity, maybe an intersex type identity? Less of "born in the wrong body," more like "what in the sweet jesus is going on with my endocrine system?") I've never heard an intersex person (coming from the intersex locus) clambering for being included in the initialism, but I've not gone looking. I stand to be corrected. It's usually bad actors trying to use intersex for their own devices... looking at you, T.