It is neither ethical nor vegan to breed and kill animals to feed another animal.
What those animals ate in the wild when free of human ownership is their business. Once human captives it is the humans who take responsibility for who dies and who lives
Pet snakes not native to the country they are kept captives of would not survive in the wild so totally unnatural to breed and kill animals for them there.
If someone has to die....then it is common sense that it is ethical to decide based on numbers of lives involved.
It is clear if vegan then getting such animal as snakes and lizards is a non starter as it would mean killing bred by humans many animals to keep 1 alive.
Cats and dogs have vegan pet foods available to them....i have both vegan fed cat and dogs for example. The small market of reptiles however has not got supplies of vegan nutrients for them to date...and unlikely to....although of course feasible....nutrients are what any animal needs to thrive on so with knowledge of the specific protein etc nutrients it would be possible.
In the case of a "pre vegan days" such snake type pet of course the matter is more difficult to face a decision about.
"In our faces" animals get naturally more attention and therefore given more "importance" disproportionate to other animals "not in our face"
What would i do personally ?
Realising that release of these would mean their deaths and cost of repatriating them to their natural environment a non starter ?
I would kill them.
I would choose...between killing 1000's of defenseless bred and killed by humans rats and mice or baby chicks etc....and killing 1. Either way....i am killing.....so i would base my decision on the numbers of lives involved.
However i have killed animals in pre vegan days.....so know what killing animals means to them.
I just could not justify killing 1000's rather than just 1 is my point.
The problem of just buying dead animals is that it avoids hearing and seeing their fear and pain when being killed by us. It makes it easier to just buy them dead already killed by someone else.
I do add....that if someone dumped on me again as did happen another dog or cat ...if not rehomed in 1 week to a vegan feeding home I would kill the dog or cat. For the same reasons.
We all let dogs and cats die by not adopting those in rescues every day everywhere. We just do not do it "in our faces" is the point. So saving 3000 chickens lives that someone feeding non vegan would be killing to feed just 1 cat or dog is a no brainer for me as a vegan.