There are only two sexes, so bisexual covers it, but clearly isn’t special enough.
While some "pansexuals" are bisexual, I think a lot are, in old money, what you would have called heterosexual.
The author of this article is a biological woman who married a biological man. Husband then identified as a woman and author identified as non-binary. So it's now classed as a queer/pansexual relationship.
After divorcing the first husband, the (bio female) author married a biological man who, it seems, still identifies as being a man but the author doesn't identify as being a woman so that is also a queer/pansexual relationship.
We get a lot of these in the LGBT community these days - People who identify as queer or pansexual but whose relationships (in terms of the biology of the people involved) are all heterosexual.