https://github.com/clojure-emacs/cider/pull/3272 a step forwards to a single jack in command 😉 With this we connect nbb and friends with cider-connect (alias cider-connect-cljs) - making the cljs repl to the "plain" repl. The current result is I can use the most default connect command to an nbb (scittle, joyride) server and it works.
One of the next things it that load-file doesn't end up popping an error buffer like usual. When using nbb.
Also the error overlay is still just sort of a fallback.