I have something like this in neovim/fennel:

(defn shadow-select []
  (some-async-fn
    (fn []
      ;; prepopulate ex mode with something like "ConjureShadowSelect "
      )))

(noremap :n :<localleader>sc ":shadow-select<CR>")

Looks like https://neovim.io/doc/user/builtin.html#feedkeys() is helpful here

Yep, was gonna suggest just feeding keys into the editor too 😄

Also you can create mappings in lua (fennel) to lua functions directly. I'm out right now so can't link, but you'll find it in conjures source code under the mappings.fnl module I think

Right, I've been learning a lot of fennel thanks to Conjure's source code! The thing is I usually have different shadow-cljs build names, so I rather prepopulate ex mode with :ConjureShadowSelect