David Kimura PRO said about 2 years ago on Hotwire Dashboards :
  It should work with Rails 6.x. However, you likely had turbolinks in that application and you would have to convert it over to Turbo (hotwire) to work properly.

As far as the modal stuff goes. This can get a bit trickier. Likely, I would have an empty turbo frame tag in the layouts for the modal. When you click the Edit Comment button, it would make a request back to the rails application for that comments#edit. From there you would have a turbo_stream response and an associated edit.turbo_stream.erb file which would then replace the empty turbo frame tag in the layouts with a partial which had that turbo frame tag and the modal information. You would then have, within that partial, a stimulus controller something to launch the modal when the controller connects. Hope this makes sense.