Completion-at-point and completion-in-region

The tab completion command ‘completion-at-point’ command is usually bound to ‘M-TAB’ or ‘TAB’. Tab completion is also used in the minibuffer by ‘M-:’ (eval-expression). In case you want to use Vertico to show the completion candidates of ‘completion-at-point’ and ‘completion-in-region’, you can use the function consult-completion-in-region provided by the Consult package.

(setq completion-in-region-function #'consult-completion-in-region)

You may also want to look into my Corfu package, which provides a minimal completion system for ‘completion-in-region’ in a child frame popup. Corfu is a narrowly focused package and developed in the same spirit as Vertico. You can even use Corfu in the minibuffer.