Hydrogen peroxide in the ear will do nothing for flu virus in your other regions. However, it is good as you say for cleaning the ears not more than once a month because it will dry the ear canal if done too often.
I’d say if you feel you are coming down with a Big Flu, get someone to gather clear liquids for you and stay away from society.
My wife started to come down with the flu a month ago and H2O2 brought it to an immediate halt. I haven’t had a cold or the flu in decades thanks to hydrogen peroxide.