I don't think that's true. Even a cursory search turns up, as the first response, this:

NIH has received almost $4.9 billion to date to fund important COVID-19 research on diagnostic tests, vaccines, and treatments. More than $940 million came from the Coronavirus Aid, Relief, and Economic Security (CARES) Act in March 2020, with supplemental funding coming from the U.S. Congress .

Edit: I guess that you could argue that it wasn't all for a single drug