Was looking to purchase a Dilophoboa card, accidentally bought an Armormata

Is there a way to revert this purchase so I can buy my snake?

Unfortunately no. I mean you can try reaching out and emailing support, but in past cases they kinda just say tough luck and you have to move on.

Iā€™d say just sell/hatch and sell your copy of Armormata and save up the lost DNA for Dilophoboa.