There are two questions to consider, has COVID-19 been faked, and could it have been faked?
The first question is obviously no. If you base your opinions on evidence, there is overwhelming evidence that it exists from reputable sources, against a few nutters with wild theories about 5G radiation.
The second question is less obvious. It's perfectly plausible that global governments could fake a virus like this if they thought it was the best way to meet their ends (whether evil or otherwise). Experts can be paid off, people willing to say the right thing can be made into "experts" while the people who know it's wrong are dismissed as idiots.
Most conspiracy theories can be likened to this. Something could have been faked, therefore people want to investigate whether it has been. If it fits their world view, if they would prefer it to be fake, then they will find the evidence to "prove" it.
I like to think of the holocaust at times like this. I wasn't there so I have to rely on evidence and expert opinion. An overwhelming amount of proof in fact, in the form of eyewitness testimony, archival evidence, archaeological remains showing that it did happen. Against this there are a few blatant racists who come up with frankly ludicrous evidence to the contrary. The holocaust obviously happened. But that does not mean that a government, or group of governments, could not fake a similar atrocity if the circumstances were right and it suited them.
The fact that something was real does not mean that it would have been impossible to fake, if that makes sense. Therefore it should be no surprise that some people go down the conspiracy route, sometimes with the best intentions, often not. With holocaust deniers the answer is usually that they are racists. With COVID deniers, I'm not really sure what their angle is.