Using a USB-C phone with Power Delivery is ideal here, as it allows the phone to be powered while also communicating with the Arduino over USB. The RemoteXY app is built specifically for this purpose.

[Scott-28] recently sent in a particularly well-documented project that turned an antique rotary phone into a digital kitchen timer using an internal Arduino.

This product is courtesy of It was super easy to make this mobile tracked platform and radio-controlled useful for building robots and other systems. It uses Arduino to run the logic to control it ...