Hello,
You can now create a Gannt chart with Plotly if you would like to go that route.
Please see here for a clonable example.
Also, Plotly figures can register click events back to the user, therefore, two-way interactivity is possible using standard Anvil techniques. For example, something like this shows clicked data being sent back to the user, which can then be updated.
Please see here for more details on how to identify the clicked data in a Plotly chart.
This seems like a very promising way to accomplish what you’ve requested as you now have a nice combination of a grid style display that is actually a two-way interactive chart.