Yeah, that paper came out last month. It’s real, but not very practical. The hacker has to be line of sight to the device’s microphone, and in most cases the laser is visible to people. So the odds are high that the attempt would be noticed even if it was possible.
It makes for a good magic trick, but real life burglars have easier ways to get into a house. I suppose a malicious ex might be able to use the method to gaslight a victim, but other than that I wouldn’t expect to see it used in real life.
The following is a good article with some manufacturer follow up:
A burglar would have to arrange a perfect combination of locale and timing to get a voice assistant to unlock a door when the owner isn’t home. Plus, the smart speaker would have to be visible, without obstruction through a window. And, the smart speaker would need to be connected to something useful like a door lock without a PIN code required to actually enable a malicious act to occur.