App Store now supports unlisted appssource • developer.apple.com
Release your apps that aren’t suited for public distribution as unlisted on the App Store, discoverable only with a direct link. Unlisted apps don’t appear in any App Store categories, recommendations, charts, search results, or other listings. They can also be accessed through Apple Business Manager and Apple School Manager. Apps for specific organizations, special events, or research studies, or apps used as employee resources or sales tools are good candidates for unlisted distribution.
Such a nice policy change to see.