I have found plenty of 1 off manual options for 3rd party HTML chart rendering outside of KNIME. There are also paid services that I could integrate via API with my KNIME workflows.
https://www.datawrapper.de/ - is a great example of both a free manual workaround and expensive API option.
It is a shame to not be able to render a simple standalone interactive HTML chart or dashboard which is already built directly in KNIME. Obviously this is a limited use kind of thing. Standalone HTML is only useful for basic summary visualizations because it is only feasible to embed limited data. Server would still be needed for complex dashboards requiring full data detail.