Slice a DT table after other filters have been applied

I posted a question on StackOverflow a few days ago. Would love get a few suggestions so I added a bounty (50 points). I'd like to slice a DT table shown in a shiny app after it has been sorted and filtered. I tried a few things with dataTableProxy but that didn't give the desired result. See the StackOverflow post linked below for details.

Thanks