That's not how PCR or antigen tests work. PCR tests use 'primers' which link to specific sequences present in the target RNA (SARS2, like all SARS and coronaviruses, uses a single strand of RNA), and then multiply those sequences (https://en.wikipedia.org/wiki/Polymerase_chain_reaction) which are measured by pushing them through a gel with an electric charge (gel electrophoresis), which leaves bands on the gel media used identifying the size of the pieces, which is pretty specific regarding particular segments of DNA and RNA, and antigen tests which link to antibodies in the sample, that flouresce under UV light, revealing the presence of the antibodies.

I am unfamiliar specifically with exosome tests, or which specific primers are used by which specific PCR tests, which is a major question regarding this very issue. Are those primers specific to SARS2 or to all coronaviruses? Published papers on the specific tests in use by specific jurisdictions would effectively answer these questions, and I am not presently able to provide links to that specific research.

I wish I was better informed in that exact information. It is clearly necessary to ascertain the nature and reason we are under threat today. We are under threat. We need to know the specific threat, and as much as we can discover as to it's nature. Other than the pandemic, about which much is variably published and known, we certainly face food insecurity, even if only due to the Grand Solar Minimum ongoing that halved harvests last year, and possibly the most existential threat to everyone is the ubiquitous increasingly draconian imposition of martial law in every jurisdiction, from America to China. On top of that the increasingly fluid geopolitical contest continues to grow the threat of expanded military conflict, which could quickly change everything for the worse.

The continuing crusade for oil currently devastating the ME is clearly at risk of expanding, and it's probably remarkable it hasn't already spread to directly impact each and all of our homelands.

We do need to know specifically what is being tested for, and who is using what tests. We already know we're being corralled and effectively under house arrest, more and more censored and limited to 'official' propaganda sources of information, and should expect ongoing disruptions in critical supplies, including food.

We need to act to secure ourselves against known threats and ongoing harms, while seeking the necessary information to understand those we do not have the ability to rationally prepare for because we do not have good information on them.