BTW, I have to say that the idea of young, newbie physician fresh out of residency/fellowship who only has years-out-of-date undergrad pharma research experience being paid to consult amused me. Never gonna happen.
If you want to be a consultant, you first need a national/international reputation as an expert in a particular topic. That only comes after many, many years of experience and research in the field.
You asked about side hustles---I did know one doctor who worked as expert witness for medical malpractice/personal injury cases. He was paid a standard per diem for each day he had to appear at the trial. He used his vacation days whenever he had to appear in court.