It seems like a pain in the neck because of the difficulty of writing code for Android, especially older versions, since the API’s keep changing and the older SDK’s might be hard to find and use (I haven’t tried). It helps if you can root the phone, but that isn’t always easy either. Plus, a phone-sized PC display doesn’t sound that useful. For a wall or desk display, you might be better off with an Inkplate (e-reader with reflective e-paper display) or similar.
This is about installing on a Nexus 5 which is from 2013. Sounds painful.