It looks like this, it opens a vertical popup at the bottom of the screen with fuzzy completion. Well that’s just cause doom is using Vertico for completion by default, I assume with other completion frameworks or configuration it’ll look different.

https://preview.redd.it/u9duaifg8vvb1.png?width=656&format=png&auto=webp&s=44c25fb889e109bec1f4c2a9665ad28921056cc4

I’m using doom emacs pretty much it’s default setup for common lisp, and SPC-s-i is bound to consult-imenu which gives a nice fuzzy searchable listing of all top level definitions in the current file and their type (function, variable, etc).

SPC-m-h-p or sly-apropos-package will show all public symbols in a package with their docstrings. With a prefix argument it will include all private symbols also, with clickable links to go to their definition.

What I don’t know is if there’s a way to view all top level definitions in a whole asdf system