A cafe, maybe not. A meeting room, likely yes. There at least you can declare that a hearing aid is used. The very point of the device is to jam other microphones.
Not going to last very long, though; ultrasound filters will soon appear on all relevant gear, including mobile phones.
((Just wait until some scrappy thesis describes how to determine character being written by pencil based on the vibrations of sound being made from the friction between a carbon based utensil and a paper pulp based medium such that the intended letters can be derived based on the length, count and direction of the audio signals derived from the sounds of the writing utensil against the medium.
I actually AM licensed as a patent agent, but I'm not practicing so I can't get you that patent.
However with ultrasonic filters - you could cone of using this.
Then such approaches have often been used like vibrating windows to curtail laser microphones and yes the trick of taping a vibrator to the window does work - though not in keeping with your boardroom aesthetics unless your Anne Summers or the like.
Only if this technique actually gains widespread use. Even then, it will most likely only appear on gear that must still record, such as body cams. For consumer tech, this would just be additional costs, which the manufacturers are not going to bother with.
If I had someone in my conference room do that I would be extremely sketched out.