This is great! One thing, it looks like there's no data for the counties of NYC - is there a particular reason for that?

Good question and thanks for commenting, I hadn't noticed that yet because NYC is so small at a national scale. It appears that there are rows from the NYT data where the county FIPS code is missing, and one of these is denoted as "New York City". This makes me think that for some localities cases and deaths are reported for a city region instead of a county geographic unit? Or maybe it's just an error on the NYT's part?

Found an issue thread on the subject in the data's Github repository: https://github.com/nytimes/covid-19-data/issues/105 particularly: https://github.com/nytimes/covid-19-data/issues/105#issuecomment-608123741