The big issue here is that (most) Clojure libraries that interact with the rest of the world do wrap some high-quality Java libraries (JDBC, web servers, etc) s

The big issue here is that (most) Clojure libraries that interact with the rest of the world do wrap some high-quality Java libraries (JDBC, web servers, etc) so Jank would start afresh here. CLJS has the same issue, of course, while Graal doesn't.