https://www.techradar.com/news/the-ipad-finally-works-with-a-mouse-through-a-hidden-ipados-feature

The absolute biggest change to the iPad that Apple introduced via its new iPadOS received zero mention on stage at the WWDC 2019 keynote: mouse support. Eagle-eyed software developer Steve Troughton-Smith discovered the new feature buried deep within the first iPadOS beta release.

Hello mouse support on iOS 13! It’s an AssistiveTouch feature, and works with USB mice. @viticci nailed this pic.twitter.com/nj6xGAKSg0June 3, 2019