I'm trying to build something like a sales report where country-level sales aggregate to regional level and can be seen through expand/collapse button at the regional rows. For example if I have a table like:

Then I want a resulting starting table to be

and i can click on a button next to "North America" to see the country-level details below.

It seems like the only way to do it in Shiny is through datatable and manipulating the callback functions, which require quite a bit of javascript knowledge (that I don't have). I did find another answer posted here that got me started. But there are still some key differences that I wasn't able to figure out (for example, showing both top-level label AND the top-level sales data at the same time, as opposed to only showing the top-level label in the other answer).

Could anyone give some advice on how to go about this? Any help would be greatly appreciated!