This is right up there with claiming that birds aren't real...
The SARS-CoV-2 virus has been isolated, imaged, and genetically sequenced thousands of times. Whole genome sequencing is how the variants are tracked. The entire genome for SARS-CoV-2 including all the variants is available online for the entire world to see as are all the images which have been taken of it.
The FDA document you reference is for the EUA for the CDC's internally developed RT-PCR test. That EUA was issued at the very start of the pandemic and the CDC didn't have an isolate available at the time for direct testing. But if you understand the nature of RT-PCR tests, you understand that it's irrelevant because all you need is to be able to positively identify the specific nucleotide sequence unique to SARS-CoV-2. If you can do that, you can do a positive/negative test even if you have to use a modified virus to validate it.
But if you want to pretend that 7.9 Billion people are all part of an elaborate scheme to trick the 500 people who are convinced the virus doesn't exist, you go right ahead.
"In the U.S. it is 99.97 percent under age 70. Under age 20 it is 99.997 percent or a statistical zero in other words."
Survival rate for people 50-64 years old is 99.4%. For those 18-49 years old it's 99.95%. For those 17 and under, it's 99.998%. Given a current 0-17 population of 61 million, that's 1,224 deaths. I'm guessing that being told "it's a statistical zero" is little comfort to the parents of 1,224 dead children. What do you think? Do you think it's a big relief for them?