Ellioto Someone had created a thread on this very same question some years prior (circa, 2019). You may want to check it out if you haven't already.
Also, just to confirm, I guess your query would essentially rule out Lamia's if I am not mistaken. Lots of people in the aforecited thread cite Lamia's, and Lamia's are half-human/half-snake hybrid creatures and not full-on snake-like creatures like the vipers from Xcom 2.
