[dkn]

Are intersex or transgender considered to be viable sexes though?

What seems reasonable to me is M/F/N where N is not capable of reproduction due to some kind of outlying error, so they cannot be a part of sexed reproduction. Are they omitted?

Sex and reproduction seem binary to me and most people. We should ignore technological or medical assistance and sort those results through the gender buckets which are more important to how they are perceived semantically, as you said.