The final update of the NIH COVID-19 Treatment Guidelines was on February 29, 2024. PDFs of the Guidelines can be downloaded until August 16, 2024, when the website will be shut down.

Not that the site was very good. Their Prevention of SARS-CoV-2 Infection page mentions masks once on the whole page and does not mention nasal sprays:

The risk of SARS-CoV-2 transmission can be reduced by covering coughs and sneezes, wearing a well-fitted mask around others, and isolating when experiencing symptoms. Frequent handwashing also effectively reduces the risk of infection.

Vaccination is the most effective way to prevent COVID-19.

Older versions of their PDF mention N95s. The only mention of N95s, other than recommending them for healthcare workers, is to claim that surgical masks are just as good:

There is evidence from studies of viral diseases, including SARS, that both surgical masks and N95 respirators reduce the risk of transmission.6 Moreover, surgical masks are probably not inferior to N95 respirators for preventing the transmission of respiratory viral infections; a recent systematic review and meta-analysis of randomized controlled trials that compared the protective effects of medical masks and N95 respirators demonstrated that the use of medical masks did not increase the incidence of laboratory- confirmed viral respiratory infections (including coronavirus infections) or clinical respiratory illness.

(That is incorrect.) The latest version does not mention the existence of N95s or KN95s, it just says “a well-fitted mask”. And N95s and KN95s are not mentioned on the site itself, outside of these PDFs.