It is highly illegal in the United States to practice medicine without a license.
It is also illegal to prescribe medicines or therapies without first establishing a "professional relationship" with the patient.
For example, you could be chatting with the world's greatest physician at a casual party. You learn that she is a world-class expert in exactly your disease.
That physician cannot legally write you a script for a medicine or piece of medical equipment. She could lose her license if she did.
In fact, she cannot know if you have the disease you claim that you do. She has no assurance that you won't sell those drugs on the street or if you have other conditions that contraindicate her first-choice in drugs.
What medical school did she graduate from?
By what magic can she mandate medical equipment like a mask without knowledge of each patient's propensity to depression, allergies and sinus infections?