Lisps are modern environments. Which is why they're implemented in themselves.
But it would have a lot of braces so junior programmers wouldn't be able to use it and so it's a non starter.
That worked for Java, where a lot of people are stuck on the JVM for legacy reasons, but yearning to at least be able to work in a more ergonomic language. Go lives in a different social environment, though. Nobody's stuck on Go because they've got 25 years' worth of massive legacy Go monoliths that they can't just chuck out the door. They're on Go because Go is what they want. And I'm pretty sure, given that they're invested in Go, that a dynamic language with a heavy focus on metaprogramming is approximately the opposite of what they want.
Just doing a syntax translation into an AST might not be enough to implement an actual Lisp on another language.
That said, Hy is still a nice language, and very well thought out. It's just that billing it as a lisp dialect for Python (as the project's website does) might lead to some false expectations. That GH thread I linked above is a great example of this. There's a lot of good, careful thought going into the design of the language. But it also has this sentence in the opening comment: "Hy is not Clojure, nor Common Lisp, but homoiconic Python." If you're interested in a Python variant with good macro system, this is it.
(Also, I'm not sure it necessarily disqualifies Hy from being a lisp. There are too many different conflicting opinions about the definition of 'lisp' for me to want to say either way, and, while a lot of good and insightful things have been said on the subject, I've personally always found that particular argument to be rather boring.)
(IIRC the ‘gisp’ project takes that approach even further: it transpiles a Lisp to the AST, and then spits out Go code that would generate the same AST: https://github.com/jcla1/gisp)