Thanks Dean. I'm thinking that list of 3 packages (Plotly, Leaflet, at DT) are just a few examples because, on that same site at
https://rstudio.github.io/crosstalk/shiny.html, the crosstalk examples use 2 packages: d3scatter and ggplot2 (and do not use Plotly, Leaflet, or DT).
I'll definitely keep an eye on that page as it has an invitation for htmlwidget authors to add their widgets to the list.