I'm not a doctor--but you cannot blindly trust them anymore. Below suggestions are based on this article: https://www.jewishpress.com/news/us-news/ny/scientists-study-coronavirus-attack-on-hemoglobin-test-new-treatments-with-old-standbys/2020/04/10/

Ventilators cause more damage than they help. Breathing capacity is fine, the problem is that the blood is unable to absorb the oxygen. That's why ventilators CPAP don't help, but the constant air pressure tears up the lung tissue. (which btw doesn't improve O2Sat)

He should be getting a gram of Vitamin C every 3-4 hours so that his lung cells can heal from the damage caused by the virus in the blood cells that flow thru the lungs (which are visible in x-rays as tons of white dots)

HCQ is useless at this point, but anti-biotics are still very helpful to fight secondary infection in the lungs.

Japan has a treatment Avigan that's useful in late stages when both lungs are involved. DexaMethazone is a great steroid that has huge results. They gave that to Trump, but his O2Sat never dropped except once, anyways.

ECMO won't really help since his blood can't absorb the oxygen well enough. Another inexpensive treatment idea is whole blood transfusion, esp from people that have recovered from Covid.. This should help because their red blood cells are like reinforcements which will be able to absorb and deliver oxygen since they haven't been infected yet with Covid. Of course, the plasma part includes antibodies to fight off the still present Covid virus.

Red Blood should be the easiest thing to provide, and the improvement should be visible. Again-I'm not a doctor so I don't know how much before improvement will show up, but there's no shortages or conspiracy against this treatment, so it should be very easy to try.

Remember--Covid is a Blood disease showing symptoms of Respiratory distress. Not a Respiratory disease.