The federated in_app_purchase plugin contains a in_app_purchase_ios package and a in_app_purchase_android package.
For the most cases, people use the federated in_app_purchase, however, it is possible to use in_app_purchase_ios and in_app_purchase_android separately with more customization on both platforms.

There are currently no example apps or README documentations to guide users to use either of them and we should add those.