This has been applied for decades. Those 'ceiling windows' in art galleries are often false windows with bright daylight lamps beneath it.

By the way, the sun produces ~50.000 lux on earth's surface. That's 100 times more than in a wall illuminated office. To reach that brightness, you would need tens of kilowatts of LED lightning for medium and larger sized rooms. That's totally infeasible. Also, imagine the heat building up. It will literally be like a greenhouse in your room. So in reality, no one actually aims for the brightness of the sun. But just something fairly bright at a high ('cool') color temperature. That produces the same sensation.