I think you need to dig deeper into Swift Playgrounds. The iPad user can definitely start their own playground outside of the preprogrammed ones provided by Apple.

In addition, you as a developer can create additional playgrounds in Xcode and transfer them to Swift Playgrounds on the iPad. That means you can give the kids a basic template and allow them to fill in the code. For example, create a template with a couple of pages with the imports already complete and a basic template of empty procedures to get them started.