Oxygen supplementation means that your lungs and/or red blood cells are losing function. This most often is from a buildup of hydrogel in the lungs, a serious infection stage. COVID patients can have Oxygen levels as low as coma patients and corpses, an unique quirk of "the trickiest disease". (Get a pulse oximeter so you can check yourself)
Dexamethasone is used to reduce inflammation from dangerous auto-immune infections. This indicates a cytokine storm, reinforcing the blocked lung theory. Again, it is a serious triage measure as it reduces the ability to fight the infection.
The White House has a top-flight internal ICU facility and staff, so going to Walter Reade indicates strong concern and returning to White House does not prove convalescence.
SO, once more POTUS and staff are downplaying the danger in a desperate bid for good news in October. Consider this: The White House has more COVID cases than New Zealand! I wish we had a woman President. They know how to debate there and control a pandemic at the same time.
Q: How do you keep Trump from walking out of his quarantine?