https://play.google.com/store/apps/details?id=org.endmyopia.calc
AR-powered Diopter Calculator for Android. The phone needs to support Google's ARCore in order to run it. Check if your device is supported: https://developers.google.com/ar/discover/supported-devices
Note that it measures distance to the tip of the nose, not to the eyes, so make sure you're looking straight on the phone, no head tilt. Please use in a well-lit room.