I am doing a science fair project on a dual-axis solar tracker on Raspberry Pi 4. I currently own a Samsung Galaxy S9 Plus with Android 9 Pie and I wan to know how to use it as a monitor screen for the Pi 4 since it would drastically reduce cost and it would be small enough to bring to the fair with me.
By the way, if there is a way to use it, how do I get back to the Android OS?