Thank you, thank you Ven. @vimalanyani 
Okay, I edited my original post to clarify what I’m looking for. Which is the explanation of how to deal with the obstructions for bhikkhunis. Will have to wait for Ajahn @Brahmali to grace us with his presence and wisdom, if he’d be so kind.
But yes, I’m mainly interested in what the Pāli texts may have (or don’t have!) to say in light of non-cisgender/non-binary ordination options—especially since they seem to place more emphasis on physical sex characteristics rather than on gender.
Based on the bhikkhu side of the khandakas, I believe one could very successfully conclude (as Ven. @Vimala has) that the texts say the only requirement (as far as gender is concerned), is that one have male sex characteristics.
(Edit: I got a bit ahead of myself there with the Pāli! Hehe, so I’ve removed my Pali comments)