They include a 7″ touch screen as an example. I have tried doing some prototype cases, but so far I don’t have a case which lets you cleanly mount the touchscreen. Also, if you go with the touch screen, or an external monitor, you may also want a keyboard. I have this wireless keyboard. It includes a trackpad, and has worked well so far.
Here is a google sheet with the Bill of Materials broken out on a per-bot basis.