With on change event on the category and baseline, you could probably retrieve the required data set and pass it on to the chart widget. Also you may need to refresh the entity used as the page parameter.
- With how you are managing it now, you cannot do it. Because listen to widget will only take 1 Category. It cannot take multiple category.
- You may have to fix it differently. Make the category drop down select multiple item
- On change of category call a Microflow and accumulates the data needed from all selected category to build the chart
- You can probably work with NPE (non-persistent entities) to collect the data needed for chart
- Make your chart work with NPE data