I was looking for something like HMR for client side reloading a little while ago (HTML, CSS, etc), and ended up with just using the CLI of Browsersync[1] with a barebones config. It works, but feels shoehorned and wonky.
It would be nice to do this with something native to Deno, which this HMR implementation seems to enable!
1. https://browsersync.io/