https://www.hindawi.com/journals/ecam/2021/5592042/

They used hydrogen peroxide to successfully treat the signs and symptoms of patients diagnosed with COVID-19 [9]. They base their treatments on a combination of oral, intravenous, intramuscular, and nebulized hydrogen peroxide. Their approach has resulted in zero deaths and the recovery of 107 COVID-19 patients [9].

you can add OTC peroxide to your water.

A nebulizer is inexpensive to buy.

you don't need to buy food grade peroxide and dilute it like some sources say