jj68 Like the title says, is the official 7in Pi touchscreen the largest supported screen? Can't find a list. Cheers.
IKS It depends on the screen. Almost all HDMI/USB touchscreen should work as long as there are Linux drivers for them included into the mainline kernel. We have also started to track all tested screens here: https://help.emteria.com/kb/devices-rpi-3