Use case

https://developer.apple.com/news/?id=01132020b

Support for Multitasking on iPad is strongly encouraged. Adding support for multiple windows [...] will ensure your app delivers a modern and complete experience on iPadOS.

See desktop efforts at #30701
Catalyst support at #33860

• https://developer.apple.com/design/human-interface-guidelines/ios/system-capabilities/multiple-windows/
• https://developer.apple.com/videos/play/wwdc2019/212