Searching in subdirectories and open with default app

Hi everyone! I am starting to use EMacs doom to take notes and organise my digital system (non programmer here). I am currently trying to build my workflow and I didn’t yet found a solution for the following: searching recursively in all subdirectories and open one file among the result with the default app. I have tried to use projectile and it works for searching recursively but I am not able to open files with defaul app (e.g. a pdf). Is there a way to achieve this? Thanks for the help

(defun open-file-externally (file) (call-process (pcase system-type (_ "xdg-open")) nil 0 nil (expand-file-name file))) (defun dired-open-externally (&optional arg) "Open marked or current file in operating system's default application." (interactive "P") (dired-map-over-marks (open-file-externally (dired-get-filename)) arg)) (global-set-key (kbd "<f9>") 'dired-open-externally) Press `f9` when the desired file is under point. `xdg-open` will use the system default apps. Define system default apps with: `xdg-settings` or with: `xdg-mime`. [Source](https://old.reddit.com/r/emacs/comments/paqvav/how_to_open_different_types_of_file_with_one/)