A company in Spain has been making a holster for law enforcement. It is called the Automatic Holster. It is designed for LE carry where a round is not chambered. With a fluid motion you push the pistol down, chambering a round while simultaneously removing the hood and retention. Then you draw the firearm out, completing the chambering sequence and the firearm is loaded hot and ready.
Here is a comparative video between a traditional draw and chamber vs their Automatic holster. I feel as though it is exaggerated a bit. They fire the round as soon as the gun is level. But they seem the exaggerate standard draw by firing at almost full extension. Also you can see their rushed shot induces a stove pipe malfunction.
They also make an even faster model called Thunder. It is designed so that the gun is carried empty chamber, since it is lot loaded the trigger does not need to be covered. Rather than a down and upward draw movement, you just push the gun forward to load and draw. As you can see in the picture above, the acessory rail is not incumbered so any light or laser would be compatible with this holster.
For further information you can check out their website at automaticholster.com.