iOS 14 brought the introduction of App Clips which function as a small portion of the app that can be accessed regardless of whether you have the full version of that app download. These App Clips act similarly to QR codes when you use your iPhone camera to scan them.
This year, with iOS 15, the integration of App Clips gets even better as developers will soon be able to integrate them into their websites. Initially, developers could add a small banner that lets users know if there’s an App Clip available. Now, an App Clip-enabled website can show banner full-screen when you’re browsing that site.
Apple is helping developers in updating their websites easily by testing their App Clips locally and using ARKit for discovering new App Clips. You can read more about what’s new with App Clips in iOS 15 on Apple Developer’s website. Both iOS 15 and iPadOS 15 are slated for release in the Fall.