How to add new option/ delete option from ellipsis/action menu

Those are not added by Streamlit, but by Altair. Unfortunately, there is limited customization available, basically you can

  1. Not show one or more of the options
  2. Not show the ellipsis at all

You can read more here GitHub - vega/vega-embed: Publish Vega visualizations as embedded web components with interactive parameters. – see the entry for “Actions”