Plot doesn’t yet support dual-axis charts, which are not recommended.
There are however several ways to “hack” this.
For example, by using the Plot.normalizeY transform (or an ad-hoc Plot.mapY transform).
Also, since Plot is just a function, you can call it with various arguments in a loop:
html`${["cases", "deaths"].map(cause => Plot.plot({
……… Plot.line(data, {y: cause… }}) … )
)}`
Faceting is really about plotting various “facets” of the data over the same scales, but by normalizing the data, you can hack it to do more things, like in Plot scatter plot matrix / Fil / Observable . (This is however another order of difficulty, and I’d recommend to try one of the approaches above.)