Don't even need fully auto weapons anymore...
https://gizmodo.com/this-trigger-happy-glove-lets-you-simulate-machine-gun-1797434487
That looks like a horrible product. I can't quite see exactly how it is used, but it really looks like it would alter the way the firearm is held. I clicked the link and saw a little video and they show a woman using it with a semi-auto hand gun and she absolutely doesn't have good control of the weapon as it fires. It seems like it makes a gun far less safe, and not because it fires many rounds in a short amount of time, but in the way it is activated and deactivated, although I can't fully tell how that happens.
I don't see why this product would be desirable at all for any legitimate use. You can fire a semi-auto rifle (like an AR) pretty damn fast as it is, but with more control and accuracy. So even if you're talking about the zombie polar bear apocalypse. or fighting government tyranny, just a regular old semi-auto is the better choice, imho, than that device.