It's possible that "Cardverse Hetalia" refers to:
* Fan-made content: Individuals may have created their own stories, artwork, or other content featuring the Hetalia characters in a setting where they are personified as playing cards.
* A specific fanfiction/art series: You might have come across a specific story or artwork online using this term, which you could try to find by searching for it with more specific keywords.
* A misunderstanding: It's possible there's a misinterpretation of the term or a related concept.
To help understand what you're looking for, it would be helpful to know:
* Where did you encounter the term "Cardverse Hetalia"? (e.g., a specific website, forum, video, etc.)
* What context was it used in? (e.g., a story description, an art piece, etc.)
With more information, I can provide a more helpful response.