I pretty much consider all corns in the hobby to be hybrids at this point, unless it is an actually lineage traced animal (e.g., @pcexotics locality corns)… Same can probably be said for many/most milk snakes and N. Am. rat and king snakes… Also, a huge portion of the chondros in the hobby and a fair number of the carpets would likely fall under this umbrella
As far as what hybrids have been produced… I think that is going to be tough because of situations like my above mentioned - it is pretty much known that there is hybrid blood but we all just “pretend” that they are not and so people will mentally gloss over them.
You will also run in to cases like the “Albino alterna” which, historically, are known to be hybrid in origin but a huge portion of the hobby is not familiar with that history so they refuse to believe that they are hybrids
With regard to “viability” and “health”, Riley touched on this but I will add in what kind of “viable” are you talking about?
Ability to live a healthy captive life is one kind of “viability”. Ability to breed another generation is a different kind of “viability”. That latter also opens another door - is only one sex reproductively viable (e.g., are the males sterile while the females are fertile)?
Also add in, are the reports of viability actually valid? I know for years people used to say that ETB x ATB hybrids never made it to a year but @warren_booth has one that is, I think, approaching three years of age
So lots to unpack there
A (very incomplete) list of hybrids that I am aware of:
Pueblan/Honduran/Sinaloan/black/all the other milks
East rat/West rat/TX rat
Yellow anaconda/green anaconda
Green Sanzinia/Mandarin Sanzinia
I know Thamnophis and Neroida hybrids exist, both wild and captive generated
I know there is a Bothrops hybrid out there but I do not know what species make it up
That is all the snakes I can remember at the moment
I am not as well versed in lizards but I know hybrids exist for
Beardies are all hybrids. ALL of them
Leopard geckos are pretty much all hybrids
I am sure there are more I am unaware of
There are hybrid Sulcatta/leopard tortoise, RES/YES, and box turtles