.. but doctors said testing dead bodies is unreliable and they won't do it..
No. Doctors are scared shit about cutting up dead covid bodies. The local university hospital has done post mortems on 20 bodies (surgeons volunteered) which had serious conditions and found covid viruses everywhere, in masses. So this is very dangerous thing to do. Until recently, the WHO advised against doing it. In a nutshell, it was seen that giving the oxygen treatment was useless in all 20 cases as the lungs were incapable of taking up enough oxygen.