Here is the list of FDA approved and disapproved Covid-19 treatments and prevention

Approved

Dexamethasone

Tocilizumab

Remdesivir

Baricitinib

Anticoagulation drugs

Convalescent plasma

Prevention

vitamin D (for prevention)

vitamin C (for treatment)

https://www.health.harvard.edu/diseases-and-conditions/treatments-for-covid-19#:~:text=In%20October%202020%2C%20the,speed%20up%20recovery%20time.

Vaccines

Look here to see which vaccines are approved in the USA.

https://www.fda.gov/emergency-preparedness-and-response/coronavirus-disease-2019-covid-19/covid-19-vaccines

Masks

The FDA recommended masks for personal and community protection.

Face Masks, Including Surgical Masks, and Respirators for COVID-19 | FDA

Unapproved treatment and prevention

Hydroxychloroquine

FDA cautions against use of hydroxychloroquine or chloroquine for COVID-19 outside of the hospital setting or a clinical trial due to risk of heart rhythm problems | FDA