Luckily, although the PRIV is unrootable, the commands wm density and wm size still work when applied through adb shell with USB debugging turned on. (If you don't know how to do this, there are many tutorials out there).
The PRIV has a native resolution of 2560x1440 @ 560ppi. We will change this to 1920x1080 @ 420ppi. To do so enter the following two lines:
adb shell wm size 1080y1920 adb shell wm density 420
adb shell wm size reset adb shell wm density reset
Hope this is helpful to you. Now I really like my PRIV and get stellar battery life and SoT: