Regarding ‘engineered COVID-19’, people putting the idea forward are speculating based the expectations of people raised on movie science. I do have training and experience in this area and have read the technical discussion of the nature and origin of COVID-19.
There is no existing capacity in the world to create a bepsoke virus, made to have particular properties. I could design a research program to do so, and it would require a moonshot level effort–years, talent, many dollars. Along the way it would require hundreds of small scale human trials. Biology is a tinker’s science, it isn’t physics, the closest thing is materials science.
The understanding of human immunity, of viral stability and transmission, of cell biology, of every aspect of the what makes a virus a disease, and the particulars of a disease are all poorly understood. Biologists can’t cure asthma, can’t prevent organ rejection, don’t have a full understanding of any viral disease, even the ones that have been studied for a hundred years.
What I’m saying is, biologists can’t do the easy things yet. Nearly every tool of molecular biology is something biologists found in the wild and took home, tweaked a bit, cut the thorns off. Every one of the millions of animals, microbes, viruses is a miniature clockwork, a computer chip. Biologists have created or designed basically nothing themselves, only a few paper airplanes, a crappy happy meal windup toy or two.
The nanotech equivalent is diamond. Nanotech is a suite of tools to build and make things on the scale of atoms and molecules. If this tech has developed to point where practical applications are at hand, diamond will become common and inexpensive. Diamond is a particular crystalline arrangement of carbon atoms, it would be a pretty easy application of a nanotech toolkit. I’ve read many news stories about nanotech, predictions that it will soon mature enough to reshape the world. But no cheap diamonds, so nanotech is no where near that point today.