package-vc-selected-packages is a customizable variable defined in
package-vc.el.gz.

Value
((completion-preview :url "https://git.sr.ht/~eshel/completion-preview")
 (emacs-wallpaper :url "https://github.com/Luis-Henriquez-Perez/emacs-wallpaper" :branch "mine")
 (escr :url "https://github.com/Luis-Henriquez-Perez/escr")
 (evil-easymotion :url "https://github.com/Luis-Henriquez-Perez/evil-easymotion" :branch "master")
 (on :url "https://github.com/ajgrf/on.el")
 (outli :url "https://github.com/jdtsmith/outli")
 (zone-matrix :url "https://github.com/ober/zone-matrix" :branch "master"))

Original Value
nil

Set Customize

Documentation
List of packages that must be installed.

Each member of the list is of the form (NAME . SPEC), where NAME
is a symbol designating the package and SPEC is one of:

- nil, if any package version can be installed;
- a version string, if that specific revision is to be installed;
- a property list, describing a package specification.  For more
  details, please consult the subsection "Specifying Package
  Sources" in the Info node (emacs)Fetching Package Sources.

This user option will be automatically updated to store package
specifications for packages that are not specified in any
archive.

This variable was added, or its default value changed, in Emacs 29.1.

References
References in package-vc.el.gz:
(defvar package-vc-selected-packages ...)        1 reference
(defun package-vc-install-selected-packages ...) 1 reference
(defcustom package-vc-selected-packages ...)     1 reference
(defun package-vc--desc->spec ...)               2 references
(defun package-vc--unpack ...)                   1 reference

Find all references

Debugging
Forget

Source Code
;; Defined in /usr/share/emacs/29.4/lisp/emacs-lisp/package-vc.el.gz
(defcustom package-vc-selected-packages '()
  "List of packages that must be installed.
Each member of the list is of the form (NAME . SPEC), where NAME
is a symbol designating the package and SPEC is one of:

- nil, if any package version can be installed;
- a version string, if that specific revision is to be installed;
- a property list, describing a package specification.  For more
  details, please consult the subsection \"Specifying Package
  Sources\" in the Info node `(emacs)Fetching Package Sources'.

This user option will be automatically updated to store package
specifications for packages that are not specified in any
archive."
  :type '(alist :tag "List of packages you want to be installed"
                :key-type (symbol :tag "Package")
                :value-type
                (choice (const :tag "Any revision" nil)
                        (string :tag "Specific revision")
                        (plist :options ((:url string)
                                         (:branch string)
                                         (:lisp-dir string)
                                         (:main-file string)
                                         (:doc string)
                                         (:vc-backend symbol)))))
  :version "29.1")

Symbol Properties
custom-requests
  nil
custom-type
  (alist :tag "List of packages you want to be installed" :key-type
         (symbol :tag "Package")
         :value-type
         (choice
          (const :tag "Any revision" nil)
          (string :tag "Specific revision")
          (plist :options
                 ((:url string)
                  (:branch string)
                  (:lisp-dir string)
                  (:main-file string)
                  (:doc string)
                  (:vc-backend symbol)))))
custom-version
  "29.1"
standard-value
  ((funcall
    #'#[0 "\300\207"
          [nil]
          1 ""]))
variable-documentation
  "List of packages that must be installed.\nEach member of the list is of the form (NAME . SPEC), where NAME\nis a symbol designating the package and SPEC is one of:\n\n- nil, if any package version can be installed;\n- a version string, if that specific revision is to be installed;\n- a property list, describing a package specification.  For more\n  details, please consult the subsection \"Specifying Package\n  Sources\" in the Info node `(emacs)Fetching Package Sources'.\n\nThis user option will be automatically updated to store package\nspecifications for packages that are not specified in any\narchive."