It is partially built on the basis injected by the Clojure CLI, and is definitely dependent on the CLI being installed (at sufficiently new version) to add new libs

The former is something that Leiningen could replicate

Thank you for confirming. I don't actually need it to work for lein. I'm just trying to add hot-loading functionality to neil.el for Emacs and wanted to make sure that limiting that only for deps.edn projects made sense.