Jan says:

I would love to be able to aggregate some of the data, then view the aggregated numbers in trend graphs. Example: I may have a Category called “Self care”, in it some Tags like “Shower”, “Go outside”, “Cook/eat healthy”, … things that are good for me, and that I often de-prioritise. It would help me to see how I get better with those over time, but it’s not the individual tags that count, it’s the category. So, I would love to see a graph for the Category itself. Either as a boolean (checked if any of the Tags in it is checked), or as a number (count number of Tags checked within Category).

I think this is something that would have to be opt-in, as people may not always use their subgroups this way.