Android 16 beta reveals Google hasn't forgotten about custom icon shapes on Pixel phones
Spotted on Android 16 Beta 3

Customization has been one of the biggest reasons we love Android. Irrespective of which phone you're using, you're free to choose a launcher that works best, pair it with an icon pack, and set up custom widgets too — and that's just the tip of the iceberg. Customizing icons is an independent rabbit hole Android embraced with the massive Material You redesign in Android 12. Now, we hear there's evidence of icon shape customization as well.