iPhone 7 offers virtual home button in case of physical button’s failure
A person on the MacRumors forums drew attention to the feature after encountering trouble with their phone suddenly shutting down. Powering it back on, they were greeted with an unusual “The Home Button May Need Service” pop-up, plus the software button at the bottom of the screen.
Rebooting initially caused the error message to go away, but soon the phone’s Taptic Engine was vibrating three or four times in a row for each button press. Rebooting again left the hardware button non-functional.