In the USA? Zero chance, unless a state of emergency makes accommodations I am not aware of. If one failed, due to not spending a lot of money and time doing quality control and getting certifications, and a patient died you would be sued out of existance.

In New Zealand you generally can't due for punative damages and lawsuits for medical misadventure are few to non-existent then maybe, but I am sure red tape would still prevent it.

Maybe it could be sold as a non-medical device, call it a "Happy Fun Breathing Simulator" with no explicit purpose and people would stock up on then.