I wonder if we're in danger of p hacking here. Suppose in the scramble to contain the outbreak, everything is tested for efficacy against the disease. There will surely be some positive studies just due to luck.
Edit: "Role of epithelial nitric oxide in airway viral infection" https://www.sciencedirect.com/science/article/pii/S089158490... says NO inhibits both virus replication and latency of viruses, including coxsackievirus, influenza A and B, rhinovirus, cytomegalovirus, vaccinia virus, ectromelia virus, human herpesvirus-1, and HPIV3 and cites 10 papers for these claims.
To some extent this is self-healing, though, in that in a giant outbreak like this someone's going to try every promising-looking technique in practice and return good data on real world results.