That's my issue with determining cause of death. I don't believe you can make a determination of death simply by performing an autopsy. I would prefer a more thorough investigation.
Every state has their own definition of what a medical examiner or coroner is. In some states, a medical examiner doesn't have to be a physician. Georgia for example, allows you to be both the mayor and the coroner if you live in a town of fewer than 5,000 people. Nebraska allows a county attorney to be coroner and justices of the peace in Texas a Justice of The Peace takes care of the coroner duties. All should however, be trained in Pathology. I would prefer them all to be medical doctors.
Remember, all states also have different requirements on what triggers an autopsy or a death investigation. Not the best way IMHO that a cause of death, especially with covid 19, should be handled.