One security improvement suggestion: make a change such that when generating a (new) password in creating or editing a login item, the generated password is NOT shown in plain text before saving the login item unless the user toggles a button to see it.
(Obfuscating the password generated while creating or editing a login item while making it optionally viewable is how the Apple Passwords app behaves, as an example.) This guards against eg someone watching through a surveillance camera in a hostile environment from viewing and capturing the newly generated password before the new login item is (re-)saved and only then does the app display it in obfuscated form.