Large round (20 or 24 inch) LED or OLED display?
It's probably "possible", but very expensive per unit and carrying an enormous minimum order cost and/or very high NRE costs. 

Suggest you mask off a rectangular LCD or plasma display with a round bezel. A 42" to 50" panel would be required for 20" to 24" diameter. Such panels are mass produced for televisions and are relatively cheap.