This presumes doctors practicing medicine 2.0 have any effective treatment. For the flu, sure there is tamiflu; or COVID, paxlovid; but absent those 2, for the short term interference; the best options are somewhere between zinc lazenges, creatine, water, and sleep.
Both the flu and COVID now have vaccines, which are more effective and preventative than interfering treatments. Anti-biotics should, generally, rarely be given at early stage, unless there are significant factors, as they have both individual and population level side effects.
Now, can a glucose monitor or testing cortisol or liver proteins more often tell you something? Yes, but not with much more actionable items than eat healthy, work out, sleep more, drink less (Yes, there is hrt, glp1s - but those are unlikely to be prescribed if the issue is not significant over a longer term)