Treatments

Wikipedia has a list of drugs, a bit outdated.  I plan to do more work on this in the future.

These are certainly good:

There are quite a few papers now that say that the gut biome is messed up by COVID-19. Some explicitly say that probiotics help. See this Twitter thread for a summary.

Potentially effective?

Also see https://www.canada.ca/en/health-canada/services/drugs-health-products/covid19-industry/drugs-vaccines-treatments/authorization/applications.html

Long COVID

Prevention

These treatments have been shown to reduce the incidence of Long COVID:

Long COVID Treatments

Advice

This page has a big section on what to do if you get COVID-19.