Package external client apps in first-generation managed packages to distribute them to other orgs. Create an external client app with Packaged distribution state, add it to your managed package, and install it in subscriber orgs alongside other packageable components.
Where: This change applies to Lightning Experience in Enterprise, Performance, Unlimited, and Developer editions.
How: Create an external client app and set its distribution state to Packaged. From Package Manager add the external client app to your first-generation managed package. Create a package version and install it in subscriber orgs.