Found one https://duyet.github.io/llm-over-dns/ and far from the only one since “X over DNS” is a deeply unoriginal idea https://hn.algolia.com/?dateRange=all&page=0&prefix=true&que... and trivial to code up.
Edit: This particular demo server doesn't work. There's another LLM over DNS post from a year ago https://news.ycombinator.com/item?id=44813298 where the server seems to answer some queries but not others.
Edit 2: Actually the server in https://news.ycombinator.com/item?id=44813298 does work with queries like "what is the capital of france", I was querying with special characters like "what's" or "1+1". So yes there are people opening hosting these on the Internet.