For Python, Datapane may solve your use-case (I am one of the founders). It's an open source framework for creating HTML reports from text, dataframes, plots (altair/bokeh/plotly/folium), and files. We provide a free public platform for sharing reports on the web, and you can check out some of the things our users are building here: https://datapane.com/gallery/
It's different to something like Observable in that you import it into your existing Python environment (Colab, Jupyter, Airflow, etc.), build the reports from your assets, and push them up -- as opposed to having to do the analysis itself in our interface.