I took a look at your workflow, thanks. In this case, KNIME is doing what vanilla R does - since the Plotly object is an HTML file that references a bunch of Javascript, as opposed to a standard image file, it instead brings up the web browser to display there. I did notice that RStudio is able to handle Plotly in its viewer window, which is handy.
I’ll mention this to our devs as something to consider. We already integrate the Chromium browser for our JavaScript view nodes anyway, so maybe we could leverage that to display more complex Plotly visualizations?