Another that was roundly mocked was Trump's idea about bringing "UV light inside the body" as a treatment. Lo and behold a year or so later.. [0]

>Ultraviolet light treatments introduced into the tracheas of five critically ill COVID-19 patients appeared to be safe and associated with a reduction in the respiratory load of SARS-CoV-2—the virus responsible for COVID-19—in all but one patient, according to a study conducted by Cedars-Sinai.

[0] https://www.cedars-sinai.org/newsroom/reduced-viral-loads-se...