The standard test for displays and computers is Can it run doom?.
Basically you try to emulate (Run original software on different hardware) on the device/computer/video game
Alternative version of this is running doom on a proper device (such as PC with a fitting OS) and using the weird device (such as a calculator) as the display.
A newer test* is trying to play the Bad Apple music video with both audio and video. \
*Citation needed
Written by Erland, The owner of Erland.fi