gpgconf
Modify .gnupg home directories.
TLDR
List all components
$ gpgconf --list-components
List the directories used by gpgconf
$ gpgconf --list-dirs
List all options of a component
$ gpgconf --list-options [component]
List programs and test whether they are runnable
$ gpgconf --check-programs
Reload a component
$ gpgconf --reload [component]