Also, another suggestion : age-default-recipient and age-default-identity should probably be set to (getenv "PASSAGE_RECIPIENTS_FILE") and (getenv "PASSAGE_IDENTITIES_FILE") by default.

This could be done in a passage-setup function, and a few other functions could be added as autoloaded, such as passage-store-list and passage-store-copy. This way we don't have to load the whole file with require at startup but can do something like that :

(with-eval-after-load 'passage
  (passage-setup))

that would be triggered when the user actually uses passage-store-list or passage-store-copy.

I think this is pretty standard now in Emacs packages.