Nasal Ivermectin.
Per the article:
The SaNOtize treatment is based on nitric oxide, a natural nanomolecule produced by the human body with proven anti-microbial properties shown to have a direct effect on SARS-CoV-2, the virus that causes Covid-19.
You can try this with PVP iodine and saline. I dont know how safe for every day use but dentists and ENT drs use it.
I also use NOZIN which is used by hospitals but very expensive.
No. Diluted povidone-iodine.